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HomeMy WebLinkAboutTransmission Line Design Review of the Glennallen-Valdez 138 KV Transmission Line 1981CVEA 17/Q1 TRANSMISSION LINE DESIGN REVIEW OF THE GLENNALLEN-VALDEZ 138 KV TRANSMISSION LINE PREPARED FOR COPPER VALLEY ELECTRIC ASSOCIATION, INC. GLENNALLEN, ALASKA Prepared by INTERNATIONAL ENGINEERING COMPANY, INC. 813 "D" STREET ANCHORAGE, ALASKA TABLE OF CONTENTS ACKNOWLEDGEMENTS INTRODUCTION EXECUTIVE SUMMARY REPORT Basic Design Criteria Conductor Design Loads and Limitations Structure Design Loads Guy and Anchor Design Limits Structure and Anchor Foundation Design on Permafrost EXHIBITS 1. E. F. Lobacz, Consultant Hanover, New Hampshire 03755, "Memorandum on Review of the Solomon Gulch Hydro Plant to Glennallen 138 kV Transmission Line," 20 August 1981. 2. N. G. Banerjee, IECO 180 Howard Street, San Francisco, California 94105 "Geotechnical Investigation of Solomon Gulch - Glennallen 138 kV Transmission Line Guy Anchors," September 1981 Appendix A Alaska Testlab 4040 "B" Street, Anchorage, Alaska 99503, “Report of Observations and Soil Test Results Tower 67-6, CVEA Transmission Line Valdez to Glennallen," 27 August 1981 Appendix B Van Gulik & Associates, Inc. Park Place, Suite 409, 201E. 16th Ave. Anchorage, Alaska 99501, "Testing of Earth Anchors, Structure 67-6 Solomon Gulch-Glennallen 138 kV Transmission Line," 8 Sept. 1981. Appendix C Trip Report of N. G. Banerjee - Sept. 30, 1981 CVEA 17/Q2 3. Chen & Associates, Inc., Consulting Engineers of Denver, Colorado Letters to Miner and Miner as follows: June 29, 1979 Subject: Foundation Piling, 138 kV Transmission Line, Solomon Gulch - Glennallen, Alaska and July 23, 1979 Subject: Pile Driving Criteria, 138 kV Transmission Line Solomon Gulch - Glennallen, Alaska. CVEA 17/Q3 ACKNOWLEDGEMENT The review of another professional's work where some hurt may ensue is difficult at best. Miner and Miner have provided data and answered queries with good grace under circumstances that must have inconvenienced them greatly. We wish to acknowledge their responsive efforts and particularly to recognize their Resident Engineer, Ken Alles, who was very helpful in providing logistics advice, local information and the current data we needed to make progress in our assigned task. The prompt and cooperative action of CVEA personnel in supporting our efforts and particularly the help of Jim Palin and Jim Fillingame in feeding back important decisions affecting the scope and detail of our work as it progressed. This was essential and greatly appreciated. CVEA 17/95 INTRODUCTION In late July 1981, Copper Valley Electric Association (CVEA) retained International Engineering Company (IECO) to review the criteria and design of the 138 kV transmission line between the Solomon Gulch hydro- electric project and Glennallen. Some concerns regarding the line had arisen and needed resolution to support the goal of placing the line in service by October 1981. A group of IECO engineers and special consultants performed an extensive design review including the accomplishment of a field anchor testing program, inspection visits to a mumber of specific sites, and analyses of a substantial group of design and construction data provided by Miner and Miner who designed and supervised the construction of the CVEA line. The objective of finding answers and providing recommendations to allow timely completion of the line construction and in providing a "third party" perspective regarding probable line performance was accomplished and reported to the CVEA Board of Directors by verbal presentation and a brief interim written report on September 16, 1981. The following report is the final document intended to provide a digest of the whole effort with important exhibits attached to provide a useful record. The large collection of our work sheets, memo's and data supplied by Miner and Miner will remain in our files if further reference is required. CVEA 17/96 EXECUTIVE SUMMARY IECO has completed herewith its design review of the recently completed Glennallen-Valdez transmission line and has found no evidence that suggests any serious, uncorrected design or construction deficiency. A heavy emphasis in our review was placed on analyzing the guy and anchor installations which were of primary concern to CVEA. It was not practical or intended that every element of the transmission line be checked out. The structure vibration phenomena was not in the scope of our work and is not part of this review. Our conclusion comes from a reasonable sampling of data and the accomplishment of limited field observation. The work is believed appropriate to support this conclusion, but obviously cannot provide a basis for a "100 percent guarantee." Some of the actual construction work required field decisions based on judgments of site conditions. The Resident Engineer, Ken Alles performed a very conscientious service in applying the design criteria to the actual situations that developed during construction. Poor installations were rejected by him and corrected. Other installations required local judg- ments which were made and recorded. Some conditions exist in regard to jong time phenomena that deserve continuing attention. These conditions relate to permafrost and flood plains where the installations now in place appear satisfactory, but may be affected in the future by changes in these domains. Our recommendations follow. The Basic Design Criteria is considered as very conservative, approxi- mately doubling the minimum acceptable loading as set out in the National Electrical Safety Code (NESC) for much of the line route. Much higher loadings were used in the Thompson Pass area which has the severest wind and snow exposures of the entire line route. Some avalanche exposure exists which is relatively unpredictable. Prudent line construction in these areas is essentially limited to minimizing exposure and keeping the line reasonably accessible. CVEA will then dispose of each incident as it occurs. It seems doubtful that economic feasibility could be found to justify the heavy expenditures required to resist the forces of avalanche. This line has standby electric capacity at each end to provide power in the CVEA 16b/aal event of line outage for any reason. The accummulated experience of avalanche damage if and when it occurs will provide real data from which to judge the pros and cons of fighting the phenomena by other means. Conductor design loads and tension limitations as used by Miner and Miner are conservative. Sag and tension data were found to have no significant differences from our check calculations. The average long time tensions are low enough to assure minimum conductor vibration. Structure design loads are conservative and the actual use of structures as built are even more so. A high percentage of structures as built would be loaded at less than half the design strength. A few of the tallest wood pole structures approach the design load. No structures were found to exceed design limits. Guy and anchor design limits used the overload capacity factors of the NESC. Our check calculations showed that most of the actual guying was conservative. Two locations were considered deficient with Miner and Miner agreeing and arranging for the installation of additional guys. No other guying was found to exceed the design limits. Anchor installa- tions received a large share of attention in the design review. Because no basic tests of anchor installation in the typical soils of the area were made by Miner and Miner (some proof testing of questioned anchors had been done), it was considered useful to perform such tests at a site where some controversary had existed about an apparent anchor failure. These tests at structure 67-6 provided a useful "yardstick" for judging soil anchor installations and confirmed the rating of the anchor when installed in accordance with the specifications and in similar soils. Our sampling of other anchor installations did not reveal any reason to believe other anchors will fail. It is recommended, however, that a continuing surveillance of soil anchor installations in cohesionless (sand and gravel) soils be maintained especially in areas subject to flooding. Line patrols can easily accomplish this by observing the indicators of anchor rod movements. Where permafrost may be involved, this is equally important. CVEA 16b/aa2 Rock anchor installations were reviewed and it was found that actual field installations were to greater embedments in rock than indicated in the specifications. Limited tests had "proofed" some anchors. No movement of rods was found on our field sampling of rock anchor installations. Structure foundations and anchor piling in permafrost were reviewed as to design criteria and actual installation. Although there is little directly comparable experience for the design as used by Miner and Miner, there are many installation of power lines in permafrost soils. Based on our general experience with such lines throughout Alaska, it is considered that the structure footing criteria is conservative. The criteria for anchor piling is also believed conservative. It is recommended that continuing observations be carried out on line patrols with particular attention paid to piling used for anchors on angles and deadends. CVEA 16b/aa3 REPORT OF TRANSMISSION LINE DESIGN REVIEW GENERAL The following paragraphs summarize the extensive investigation of design calculations and field inspections which were carried out to provide a basis for the conclusions reached in this review. It was not practical, nor intended that every element of the transmission line be specifically checked out. It follows then that the conclusions come from a reasonable sampling of data and field observations. This sampling is believed adequate to support the conclusions, but obviously cannot provide a basis for a "100 percent guarantee." We are aware of the tower vibration phenomena that has resulted in several structural failures in certain tower types in your transmission line. We believe that the problem will be solved and that further failures will be eliminated. As engineers we are acutely interested in the results of your ongoing efforts to cure the problem and thereby provide useful information for avoiding such conditions in the future. We could have joined the effort toward solving this vibration problem, but our scope of work did not include such an assignment. We therefore make no further comments about this specific problem. The report considers in order the Basic Design Criteria, Conductor Design Loads and Tension Limitations, Structure Design Loads, Guy and Anchor Design Limits and Structure and Anchor Foundation Design in Permafrost. Basic Design Criteria The Basic Design Criteria for a transmission system is developed to provide for the estimated effect of climatic conditions which influence the physical loads that must be supported by the conductor, the structures and the founda- tions of the line. Temperature, icing conditions and wind pressures are the basic sources of loading which affect the strength requirements of line components. The CVEA 17/N1 beginning point for such design loads in Alaska (as in most of the United States) is the National Electrical Safety Code (NESC) which has been adopted by the State as the basic guide for design of overhead lines. Applicable editions of the NESC place Alaska in the HEAVY LOADING category of the code. The combined ice and wind loading for this category is: Tce ==-----—-—— = radial thickness (inches)----- 0x5 Horizontal wind pressure (1bs/sq. ft. )------- 4.0 Temperature (°F )----------------------------- 0 For the NESC extreme wind loading condition as described in NESC Rule 250 C and Figure 250-2: "If any portion of a structure of supported facilities is located in excess of 60 feet above ground or water level, these wind pressures shall be applied to the entire structure and supported facilities without ice covering." Extreme Wind (CVEA area) ------------------------ 13 lbs/sq. ft. atlamtemperatune (2h) potas a sa 60 "Wind velocity usually increases with height; therefore, experience may show that the wind pressures specified herein (NESC) need to be further increased." The NESC also provides that ".... the total load on a conductor ... shall be the resultant of components... (from loadings shown above)... calculated at the temperature specified (see above)..., to which resultant has been added the constant specified in Table 251-1..." This constant for the NESC HEAVY LOADING category is 0.3. In addition to the minimum loading criteria required by NESC, special jocal conditions may suggest that more severe criteria is warranted. Previous studies* of the transmission line corridor had suggested that *"Basic Design Manual", Valdez to Glennallen 138 kV Transmission System. February 1976 by R.W. Retherford Associates. CVEA 17/N2 NESC HEAVY LOADING criteria were adequate for about 90% of the line route; 1" ice plus 4 lbs. of wind at O°F for 6% of the route; and special loading of 2" ice plus 4 lbs of wind at O0°F, or 50 Ibs of wind (141 mph) on the bare wire @ 32°F for 4% (Thompson's Pass) of the route. Miner and Miner chose a more conservative criteria which resulted in the use of 1" ice plus 4 Ibs. of wind @ O°F for 52% of the route (Zone II); ls ice with no wind @ O°F for 41% of the route (Zone 1) and 3" ice plus 9 lbs. of wind @ 32°F or 78.4 lbs. of wind (175 mph) on the bare wire @ 0°F for 7% (Thompson's Pass-Zone III) of the route. The following listing (TABLE 1) of typical design loadings used by Miner and Miner on various portions of the CVEA transmission line has been developed from the "as-built" Sag and Tension Data for conductor installa- tion supplied to us by Miner and Miner for both Phase I and II of the Project. The data is grouped by Zones (see following Key Chart excerpted from the Miner and Miner 1978 Basic Design Data) which include structures numbered as follows: Zone I Structures 23-1 to 41-3 and from Structures 48-4 through 74-2 Zone II from Structure 74-2 through Pump Sta. 11 Zone III Structure 41-3 through 48-4 CVEA 17/N3 APPROX, leume STATION Wo. ‘oe STRUCTURE 13D- 4 PROPOSED — Brae TA ELEV. 1B0 ds) MERIOIAN RIVER i | 4 | ZONE IT <j = | (ELEY 1200’ tp 27007) |~_ & | i 8 Sore Si - ry ' iN © | \ | hs Sea - y - PROPOSED | : 138 KV Sos i TRANSMISSION ae 4 S| | LINE STATION z Sa | i No. 12 i | | SUBSTATION | | STRUCTURE 7422 >" | ZOnEI | (ELEV. 1600’ to 2700’%\ _|_~ i | | Vii i | ZONE IIT bint | zone (ELEV. 1000’ to/2800’) (ELEV. 300’ to 1000’ Ye i fr Ll \ Sf) eo / | oe dr A TASINA | proroseo\—|_C Biermigiah Drop zg MEALS NY TRUCTURE 48-4 2 SUBSTATION : 14.4 / 24.9 KV OC. Nsotomon GULCH GENERATION STATION Lorsw | REW (APPROX. ELEV. 2000’)! [Thompson ' poss STRUCTURE 41- -3 APPROX. ELEV. pais LIGHTNING PROTECTED, , mies RIE MINER AND MINER CONSULTING ENGINEERS, INCOMPONATED ST EELEY, COLOmADO KEY CHART R3w Conductor Design Loads and Tension Limitations Inspection of columns (6) and (7) of Table 1 shows that the maximum conductor loadings are well below the limits set by the NESC and the jatest edition of the REA Design Manual for High Voltage Lines (REA Bulletin 62-1 dated August 1980) which are the following: Maximum Design Tensions Maximum Design Tension % of Ultimate Description of Initial Final Loading Condition Conditions Conditions NESC Heavy Loading ---- 60 60 NESC Extreme Wind ----- 80 80 NESC Unloaded @ 60°F -- 35 25 REA (NESC Heavy Loads)-- 50 50 REA (Extreme Winds) ---- 70 (80) 70 (80) REA (Extreme Ice) ------ 70 (80) 70 (80) REA (Unloaded @ 0°F)---- 33.3 (20) 25 (20) ( ) REA recommendations for EHS steel wires such as the 19#5 alumoweld. The review of the design loading criteria and the design tensions for the conductors of this line as demonstrated above leads to the conclusion that the loadings selected and the conductor tension limits provided are conservative indeed. All the basic sag and tension data for the as-built locations shown on Table I were checked using the loading criteria assigned. No significant differences between our calculations and those supplied by Miner and Miner were found. Normal long-term tensions of conductors were noted to be low enough to assure minimum vibration of conductors particularly in Zone III where the greatest ice and wind loads are expected to occur. CVEA 17/N5 TABLE 1 TYPICAL DESIGN LOADINGS TRANSMISSION CONDUCTORS "AS-BUILT" CVEA LINE, GLENNALLEN TO VALDEZ Zone Loading Condition Wire Tension Cond. /R.S. Description Ice Wind Temp. % of Ultimate Location rad.-in. lbs/ft? °F Initial - Final ql) (2) (3) (4) (S) (6) (7) ZONE 1 Extreme Ice 155 0 32 61 60 (Dove/735' Extreme Wind 0 13 0 2Y, 21 Str. 23-1 Extreme Temp. 0 0 -40 25 17 to NESC-HEAVY 0.5 4* 0 36 31 25-1) NESC-BARE 0 0 60 17 12 Normal-Long Time 0 0 40 18 13 Normal-Long Time 0 0 0 21 14 (Dove/2083' Extreme Ice 1.5 0 32 64 64 Str; 25-1 Extreme Wind 0 13 0 16 16 to Extreme Temp. 0 0 -40 10 10 2522) NESC-HEAVY 0.5 4* 0 26 26 NESC-BARE 0 0 60 10 9 Normal-Long Time 0 0 40 10 Normal-Long Time 0 0 0 10 10 (19#5 Alwid Extreme Ice 1-5 0 32 47 47 2026' span Extreme Wind 0 13 0 18 17 Str. 48-4 Extreme Temp. 0 0 -70 16 16 to NESC-HEAVY 0.5 4* 0 26 25 48-5) NESC-BARE 0 0 60 14 14 Norman-Long Time 0 40 45 14 Normal-Long Time 0 0 15 LS NOTE: Column (1) Zone of line (See Key Chart), conductor/ruling span and Location Column (2) Description of Loading Condition Column (3) Amount of ice in inches of radial thickness Column (4) Amount of wind pressure in pounds per square foot Column (5) Temperature of the conductor, degrees Fahrenheit Column (6) Percent of conductor's ultimate strength - initial conditions Column (7) Percent of conductor's ultimate strength - final conditions * To the resultant of these wind and ice loads, a factor of 0.3 is added for conductor loading in the NESC HEAVY LOADING category. . Table 1 (Cont'd) x CVEA 17/N7 See Notes on previous page. Zone Loading Condition Wire Tension Cond. /R.S. Description Ice Wind Temp. % of Ultimate Location rad.-in. Ibs/ft °F Initial - Final (1) (2) (3) (4) (5) (6) (7) ZONE II Extreme Ice 0 4 0 53 53 (Dove/976' Extreme Wind 0 13 0 28 25 Str. 74=2 Extreme Temp. 0 0 -70 26 Ze to NESC-HEAVY 0:5 ‘ax 0 39 37 78-6 NESC-BARE 0 60 17 a5 Normal-Long Time 0 40 18 a5 Normal-Long Time 0 0 21 ae (Dove/1000' Extreme Ice 1 4 0 53 53 Extreme Wind 0 13 0 28 25 Str. 86-1 Extreme Temp. 0 0 -70 25 20 to NESC-HEAVY 0.5 4* 0 39 37 922) NESC-BARE 0 0 60 17 14 Normal-Long Time 0 40 18 15 Normal-Long Time 0 0 20 16 (Dove/2150' Extreme Ice 1 4 0 53 53 Str. -/99=5 Extreme Wind 0 13 0 21 21 to Extreme Temp. 0 0 -70 14 13 99-2 NESC-HEAVY 0.5 4* 0 34 34 NESC-BARE 0 0 60 13 13 Normal-Long Time 0 0 40 a3) 1S} Normal-Long Time 0 0 0 13 a3 ZONE III (19#5 Alwid. Extreme Ice 350) 9 32 61 61 908' R.S. Extreme Wind 0 78.4 0 29 29 Str. 44-5 Extreme Temp. 0 0 -40 LE 10 to NESC-HEAVEY 0.5 4* 0 17 LS 48-4) NESC-BARE 0 0 60 9 8 Normal-Long Time 0 0 40 9 9 Normal-Long Time 0 0 0 10 Structure Design Loads Structures used on this line include a wide variety of designs using wood poles, steel pole and tubular steel structures both guyed and unguyed. The following Table 2 listing types of structures shows this variety and provides a reference point for our comments. Figures 1, 2 and 3, which also follow, show results of sampling the actual as-built conditions compared to design limits for selected structures. All individual structures were not checked. Our review of the structural design limits and the actual use of struc- tures shows that the design limits provided are conservative. Based on the sampling we performed it is apparent that the line as built is safely within these conservative limits. Very few structures as built would be expected to have loadings even close to the design limits. The design limits of Zone 1 where wood poles are used are considered conservative. The structures in this zone using the tallest poles occasionally approach the design limits at a few as built locations. No structure was found to exceed the design limits at any location sampled. CVEA 17/N8 TABLE 2 STRUCTURE TYPES "AS-BUILT" CVEA LINE, GLENNALLEN - VALDEZ Approx. Qty Used PHASE I OF PROJECT Structure Type Description STX-138 Hinged, guyed X-Tower for tangent line (1° max.) STX-138G Hinged, guyed X-Tower for tangent line with overhead ground wire. ST-13 Three column, steel tube small angle (30° max. ) ST-13G Three column, steel tube medium angle with over- head ground wire ST-14 Three column, steel tube medium angle ST-15 Three-comumn, steel tube heavy angle ST-15G Three-column, steel tube heavy angle with overhead ground wire. s-“15T Three-column, steel tube tangent dead-end Sisi2 Single-column, steel pole junction structure TUS-138 Single-column, steel pole tangent double-circuit with overhead ground wire. 251 19 17 Design Loading Zone Zone Zone Zone Zone Zone Zone Zone Zone Zone Zone HT ET Il II Il 1a rT ET re Il * Individual structures of this type were not checked. CVEA 17/N9 Remarks _ See Fig. 1 * See Fig. 1 x See Fig. 1 See Fig. 1 x See Fig. 1 x x Approx. Basic Structure Qty Design Type Description Used Criteria Remarks PHASE II OF PROJECT TH-10 H-frame, wood pole for 3 Zone I Z tangent line - with an overhead ground wire (OHGW) TH-138S X H-frame, wood pole, steel 195 Zone I See Fig. i aa 2 tube X-arm for tangent line (no OHGW) ---- TH-13M Three-column, wood pole 15 Zone I zx small angle TH-14M Three-column, wood pole 9 Zone I = Large angle TH-15S Three-column, wood pole 25 Zone I See Fig. lees double dead-end TH-2S, 1, c H-frame, wood pole 37 Zone I See Fig. thru - type dead-end TH-17AL Three-column, wood pole 1 Zone I a double dead-end with overhead ground wire Steel Poles Three-column, steel pole 2 Zone I - tangent dead-end Steel Poles Three-column, steel pole, x Zone I i angle (12°) dead-end Steel Poles Three-column, steel pole, 2 Zone I a medium angle (13° to 42°) dead end. Steel Poles Three-column, steel pole 4 Zone I ms medium angle (13° to 42°) dead-end Steel Poles Three-column, steel pole, 6 Zone I a heavy angle (45° to 85°) dead-end * Individual structures of this type were not checked. CVEA 17/N10 Table 2 (Cont'd) Structure Type Description Used Criteria Remarks PHASE III OF PROJECT A X-Tower, one brace leg 31 Zone III ae steel tube, for tangent line (50 to 100 ft. ht.) B X-tower, one brace leg 5 Zone III : ** steel tube, 18° to 26° angles (50 to 80 Ft. ht.) D Portal - 4 legs, steel 5 Zone III ** tube, dead end angles (0° to 5°) E X-tower, two brace legs, 4 Zone Ilt. .** steel tube, tangent, strain dead ends H X-tower, one brace leg iL Zone III ** steel tube, tangent (45' ht.) steep sidehil} **k These structures were individually designed for each location by the Tower manufacturer. CVEA 17/N11 No further check was made by IECO. PHASE T - ZONEIL STRUCTURE 6k YS VESIGN UNITS TK-15B ST-1\5 VERTICAL / HORIZONTAL VERTICAL / HORIZONTAL S57ANS LIMIT ENYELOPE SPANS LIMIT ENVELOPE 3000 (from Miner & Miner Vota) 3000 (from Miner & Hiner Zota) ¥ 22.000 2000 5 - < © e 1900 1000 1000 2000 1000 Z000 3000 HORIZONTAL SPAN - FT. HORIZONTAL 4S¥AN- FID AT-14 STISG), STIST OH VERTiCAL ) ieeraiir. VERTICAL 7 HORIZONTAL SYANS LIMIT ENVELOPE SYANS LIMIT ENVELOPE Cfrom Miner & Hiner Votay (Grom Miner & Miner Vata) VERTICAL SPAN- ET. 1000 2000 4000 1000 2000 3000 HORIZONTAL SVAN-FT. HORIZONTAL SPAN-FT FIGURE NO. 1 PHASE I- ZUNE L STRUCTURE USE YS. DESIGN LIMITS TH -138 5X 65-1 TH - 138 4X ; ©0-| 2000 2 < w at 2 1000 ws ma ° 3 1000 2000 HORIZONTAL SPAN- FT. i TH-138 5X ¥ 70-1 =z2000 < 0 ¥ x eS) ye Pa 1000 200 HORIZONTAL SPAN - NERTICAL SPAN- FT \oQ0 2000 HORIZONTAL SPAN-FT. TH-138 3X x 75-| + 2000 a < » Y = S Yo Ww > 0 2000 HORIZOUTAL SPAN -FT. TH- eka ae ¥2000 Z » ad e \000 ws > W y O loco HORIZONTAL SPAN Oe. FIGURE No. 2 FHASE [b- ZUNE L ACTUAL VEAV-ENV LOAVING Y5.WOOP? POLE BUCKLING STRENGTH 2-E9 LONG Ps & CoA HIPNAWS/C ANT INITIATE TTA POLE 5126 é STRUCTURE No. 2-9) onas z 2-19 SONS = FAI LMAG wv ‘WN 2-09 IMU & oO 3 3 3 9 ° Ww ee Cr WANA 7) AVO1 ONIIANA TWNDY POLE SIZE & STRUCTURE No. FIGURE NO 3 Guy and Anchor Design Limits Guy and Anchor Design Limits used were those set by the NESC. These limits are applied by calculating the loads expected (those produced using the basic design criteria cited earlier) and then increasing these loads by an Overload Capacity Factor (OCF - see below) to determine the required strength of the guy/anchor system. The loading assigned to the guy after the OCF has been applied shall not exceed 90% of the rated breaking strength of the guy. Guy Overload Capacity Factors With With Wood Poles Steel Structures Transverse strength Wind Load 2.67 225 Wire tension load 1.3 1.65 Longitudinal strength (except at angles) In general 1.0 2.0 At dead ends 1.6 1565, Extreme condition Strength See Loading 10 1.0 Check calculations for nearly all of the guyed structures on the line showed that most of the guying on the as-built line was conservative. There were two structure locations where it was noted that guying was deficient. Miner and Miner agreed and arranged for the installation of additional guys. CVEA 17/N15 It should be noted here that in the application of guying systems there are varying philosophies in the practices of the industry which result in differences of opinion about good practice. These differences show in the IECO work sheets which were given to Miner and Miner in the process of our review. The philosophy used by Miner and Miner reflects the broadly used guidelines published by the Rural Electrification Administration (REA). The recommendations for design in this REA document are considered as good, prudent practice throughout the United States and other areas of the world. With the addition of the guying noted above, our sample calculations show no guying that exceeds the design limits noted. The guy anchor design and installation received more attention than any other element of the design review. The interest of CVEA in requesting that this review be performed came largely from the claims and counter- claims surrounding a particular event that occurred at Structure 67-6. The differences surrounding this event had been resolved before IECO was brought into the review, but it appeared to us that valuable information could be gained by learning as much as practicable about the installa- tions of anchors at this location. The following paragraphs describe what was learned and how we interpret the remaining sampling of anchor installations using this data. The original anchors installed vs the high strength conductor at 67-6 were replaced by additional heavier anchors at longer leads and left in place. These "used" anchors had pulled upward enough to increase the exposed anchor rod length from about 8 inches to 36 inches. Five of these anchors were tested as found and one was reinstalled in adjacent undisturbed ground in accordance with the original speci- fication and tested. The tests were performed by Van Gulik and Associates, Inc. of Anchorage and were observed by Alaska Testlab and IECO personnel. Detailed reports from Alaska Testlab, Van Gulik and Associates and IECO are included in Exhibit 2 to this report. The following table summarizes the results of these tests: CVEA 17/N16 ANCHOR TEST SUMMARY Structure 67-6 Anchor Load kips Maximum Load No. w/2" Move Kips In. Moved 1 12 12 2.44 3 12 17 4.56 5 15 19 3.94 6 14 15 4.25 7 12 19 8.9 Reinstalled Anchor 23 40 5.68 The observations and analysis of the existing anchors tested led to a conclusion that those anchors had not been instalied in accordance with the specification and that improper excavation (too large an opening), setting (not set against undisturbed material), and backfilling (poor or no tamping of backfill) resulted in inferior strength. The anchor locations related to the structure location showed also that the resulting guy tensions would have been higher than those resulting from a one to one guy slope (45°). Both these conditions (anchor installation and location) had been re-worked at the site and appeared in accordance with the specifications. It is concluded that the soil anchors TA-10C and TA-20C would perform to their rated capacity if installed in accordance with the specifications in soils approximately equivalent to that at 67-6 where the tests were performed. : Field testing of anchors at sufficient locations to provide "yardstick" data in typical soils is an important, necessary part of quality assur- ance in unknown terrain. While some information existed (existing distribution lines and Alyeska soils data) it is believed that more understanding of anchor performance in these local soils would have been useful for design Some "proof" tests were performed during con- CVEA 17/N17 struction at certain locations where inspectors felt there was some departure from the sepcifications. These tests (mostly on rock anchors) did provide additional real data to provide check points for understanding the effectiveness of anchoring. Failure of the anchors at 67-6 and other locations (with replacements made) brought awareness of the potential for other failures. More attention to installation inspection and the marking of anchor rods to provide a reference point for observation of future movement resulted. The Miner and Miner Resident Engineer, Ken Alles, assured us that the installation at 67-6 was not typical of anchor installations throughout the remainder of the project. The evidence IECO observed at other installations visited during this review confirm his statement. There is no evidence in our sampling that other anchors will fail, however, it is recommended that line patrols pay particular attention to observing anchor rod movements, if any, as time passes. Permafrost conditions are variable and could release some surprises at future dates. Good surveil- lance of anchor installations should prevent a catastrophic failure since movements in permafrost take place slowly. A field visit to several selected structure installations was made in late September 1981 by IECO and Miner and Miner personnel. This trip is reported in detail in Appendix C to Exhibit 2 attached. This visit served to provide additional perspective regarding a variety of anchor installations including some in rock. No evidence of anchor movement was found at any site. A rock anchor tested to 31,000 Ibs (by a construc- tion incident) without movement was observed. IECO recommended that anchors installed in cohesionless sand and gravel be given special attention, particularly in areas subject to flooding. No movement was noted at structure site 51-1 (where additional anchors had already been installed) or at structure 38-5. It was agreed that additional anchors would be installed at 38-5 and at 56-1. CVEA 17/N18 Structure and Anchor Foundation Design in Permafrost Steel piling were specified to be driven to depths such that the penetra- tion of permafrost is twice that of the seasonal frost layer. In addition to the general penetration specification cited, the Miner and Miner guidelines used for pile driving indicated minimum desired depths of piling for structure footings as 22 feet in permafrost and 6 to 10 feet in rock. These design criteria were developed from tests made in June 1979 with observation by Chen and Associates, Inc. of Denver, Colorado. In July 1979, Chen and Associates submitted a discussion of possible subsoil conditions and recommendations for pile driving in each. These Chen and Associates, Inc. letter reports are included as Exhibit 3. Prior to receiving the data from Miner and Miner regarding the basis for their design criteria for permafrost, IECO had invited Mr. E. F. Lobacz, consultant of Hanover, New Hampshire and co-author of "Design and Con- struction of Foundations in Areas of Deep Seasonal Frost and Permafrost" (a 1980 special report of USA CRREL) to participate with a site inspection team on review of the Solomon Gulch Hydroplant to Glennallen in early August 1981. Mr. Lobacz submitted his report "Memorandum On Review of the Solomon Gulch to Glennallen 138 kV Transmission Line" by August 20, 1981. This report is attached as Exhibit 1. More sophisticated site specific investigations can be made at con- siderable expense to determine more scientific solutions, but such actions are seldom considered prudent for transmission structures of lines of this nature. There are several transmission line installations in Alaska with lengthy experience in permafrost, muskeg, soil, rock, etc. The lines include wood-pole, guyed aluminum and steel structures, and some self- supporting structures. These installations have a performance history CVEA 17/N19 that is generally good, but includes some incidents of failures. Unfort- unately the history and details of these lines and their performance is not well documented in any one place - so the learning that has occurred rests largely in the heads of those who have participated in the design, construction and operation of these systems. It is from this base of experience that the following general comments are made in an effort to provide some useful perspective in reviewing the footing design criteria set by Miner and Miner for this Valdez-Glennallen transmission line. The experience gained with wood poles and other footings in Alaska permafrost suggests that the criteria used by Miner and Miner (resulting from the Chen and Associates recommendations) appear conservative, particularly as related to structure footings. There is not much experience that is directly applicable to the piling used for anchors where everyday loadings are at a large angle to the axis of the piling. The performance of such piling will then depend on the long term stability of the pile. There is experience with anchors that bear on permafrost and have demonstrated a good long term stability after some initial creep takes place. There is no apparent reason to expect that the basic criteria for the piling anchors is any less conservative than it appears for structure footings. A review of the pile driving records showed a wide range of penetration for the driven piling (6 to 57 feet). The following graph labled Fig. 4 shows the approximate distribution of piling penetration represented by this record of piling from structure 74-2 to 130-7. The graph separates the data into two sections of line (74-2 to 99-5 and 100-1 through 130-7) to illuminate some differences that may relate to permafrost. While the permafrost is discontinuous and sporadic throughout this line, its occurrance is much more common in the section including 100-1 through 130-7.' CVEA 17/N20 PILING PENETRATIONS CVEA GLENNALLEN—VALDEZ TRANSMISSION LINE ANCHOR PILING PENETRATION Structures 74-2 thru 99-5 Structures 100 250 -7 -I thru 130 60 50 MSs 40 S89 30 20 AX 10 50: = 2 a ONITId YOHONY JO SON 2 oO N 60 50 40 STRUCTURE PILING PENETRATION Structures |OO-| thru 130-7 Structures 74-2 thru 99-5 20 30 PILING PENETRATION — FT. MSS. 10 O° °o wo ONI Md AYNLONULS $0 SON 100 FIGURE No.4 Most of the piling installed meet or exceed the criteria cited earlier. Those piling whose penetration is less than criteria are found to be in ground that is clearly harder, probably without permafrost and in some cases apparently in rock. There appears to be no reason to expect substandard performance. In areas where permafrost could exist there could still be surprises with time. It is suggested that continuing observations be carried out on line partols with particular attention paid to piling used for anchors on angles and dead ends. Such surveillance is important in areas of potential perma- frost regardless of the sophistication of the installtion (note the Alyeska experience). CVEA 17/N22 Memorandum On Review Of The Solomon Gulch Hydro Plant To Glennallen 138-kV Transmission Line by 3} Ul WY E. F. Lobacz, Consultant : a Hanover, New Hampshire 03755 20 August 1981 Table of Contents Site INSPeGEION! eaM a cci,5 ce sical s cle ow aeeieln wala icin = cicie elena ee et eatetetate i General Statement ....... Ce plelels elsholetclasieisalciersateictsreieiersic TE Documents Examined ......-.--.s.eeee Keldeerscadaa eaeiceclaat antl T/L Foundation Design in Cold Regions .........----.---.. hal eS 2 ANGNOV AGES. etclnrsteisi sloietol op letel ew e'e\ ovo lelele olclarsicielo aleis siciee cisie’ mine iefeieis o'e.e ce lerers 3 Weather Data ...... 5.200. eee Ra feleiohets everest seelecis Bie eiscicisie 4 Design Freezing and: thawing Indices «..<..acc220..ccccccectcccccces 5 Depth) To andihiekness) Of Permafvost: sees see e cele eee clole 5 SETSMIG AGUIVIILY, esto aisters st siel5 clorcloicisl cleieisie loin oie ctels eisfoaie fel cieim cielelels 6 Field) IRSPECURON! Risarcisic1s stoisisiets tela oleleloi(oleFeteel os oie1s cicie «leicie (ole lcietcielei=iei@ als 7 Discussion of Tower Foundations &sGuy, vANGNOMS pon cris sis. -locie s/=1515)= 8 RECommendaitsiOns ery sis s/s letele ole niche Gielgiciets eieitinicisie sfeiee slciate le eietsleie = falter 9 te Site Inspection Team R. W. Retherford, IECO, R. W. Retherford Associates Division, Anchorage, Alaska G. 15 Israelson, IECO, San Francisco, California D. Steeby, IECO, R. W. Retherford Associates Division, Anchorage, Alaska E. F. Lobacz, Consultant, Hanover, New Hampshire =15 General Statement The Copper Valley Electric Association (CVEA) retained International Engineering Company, Inc. (IECO) to provide a review and make recommenda- tions on the Solomon Gulch-Glennallen 138 kV T/L for adequacy of design and construction details in general and specifically the adequacy of the guys and anchors on the T/L. This T/L must be-adequate for the services intended and, if necessary, corrective action specified before the end of the 1981 construction period. The lines operating date is October 1981. Documents Examined Pertinent to T/L 1. Miner and Miner, Consulting Engineers, Inc., (M & M) Greeley, co (1978) Summary of Basic Design Data, Solomon Gulch Hydro Plant to Glennallen, 138 kV Transmission Line (Original document, no revisions or amendments). 2. (M&M) 1979, Construction Contract, Solomon Gulch Hydro Plant to Glenn- allen, 138-kV T/L, Phase I Labor and Materials (Glennallen substation to Ernestine highway facility). 3. (M&M) 1979, Construction Contract, Solomon Gulch Hydro Plant to Glenn- allen, 138-kV T/L, Phase II Labor and Materials (Meals substation to Ernestine highway facility). 4. (M&M), Phase I Structure Sheets from structures 23-1, Station 184 + 86.834 to 74-1, Station 2827 + 80. ‘ 5. (M&M) 1978, P/P, Station 2831 to 5782 + 75.7, Phase I (Released for Construction). 6. (M&M), P/P, Station 2831 to 5782 + 75.7, Phase I, marked preliminary. 7. (M&M) 1980, Book of pile driving records for Phase I Construction Contract, P.I. 45 to Pump Station No. 11. | Other 1. R. W. Retherford Associates (1976), Valdez-Glennal ten 138 kV T/L, Basic Design Manual (CVEA). 2. Woodward-Lundgren Associates (1971), Results of Pile and Anchor In- stallation and Load Tests and Recommended Design Procedures, TAPS (Final Report). 3. REA-USDA (1980), Design Manual for High Voltage Transmission Lines, REA Bulletin 62-1 (Revised August 1980). 4. REA-USDA (1972), Transmission Line Manual, REA Bulletin 62-1. =o 5. Watson, C. E., Branton, C. I., and Newman, J. E., (1971), Climatic Characteristics of Selected Alaskan Locations, University of Alaska Tech. Bulletin No. 2, Institute of Agriculture Sciences. 6. Branton, C. I., and Watson, C. E., (1969), Precipitation Probabilities. for Selected Sites in Alaska, University of Alaska Tech. Bulletin No. 1, Agriculture Experiment Station. 7. Aleyeska (1974), Frequency of Occurrence of Daily breripi tation. Re- _ . port DM CDB009. . (This report includes Ernestine, Tonsina Lodge, Copper Center/Copper Valley School and Glennallen stations). 8. Bureau.of Reclamation, (1976), Footing tests for transmission line towers, A collection of data, Report No. PB-263-857. T/L Foundation Design in Cold Regions Philosophy A power transmission line covers an extended area and a variety of foundation conditions may exist. It is generally uneconomical to develop an individual design specifically for each structure or portion of the facility. Generally, the terrain is divided into areas of like foundation conditions, and standard designs prepared which are suitable for each of these areas. Also a number of standard designs may be prepared to cover the range of conditions, the particular design for each facility element to be field-selected in accordance with the conditions actually encounter- ed. Site_specific designs may also be prepared. Tower Foundation Designs Generally the design of tower foundations in seasonal frost areas follows the same procedure as where frost is insignificant or absent. Foundations are taken to depths below the depth of annual frost penetra- tion and precautions taken, where necessary, to prevent uplift or thrust damage aS a result of frost forces acting on the members which transmit structure loadings through the annual frost zone to the bearing or anchor- ing elements below. A tower supported. on top of the annual frost zone will experience frost heave if the freezing soil is frost-susceptible and moisture is available. Seasonal vertical movement may or may not be detrimental. If heave is differential between footings, the tower will tip and/or the structure will be unevenly stressed. If the tower is guyed, the guys and/or the guy anchors may be overstressed, and some may become slacked. Differential footing settlements may occur during the.spring thaw-weaken- ing. On a slope, progressive downward movement may occur with successive cycles of freeze-thaw. Granular material may be used to control or even eliminate detrimental vertical movement. The simplest approach is to support the tower on a granular mat placed on the surface. It is usually impractical in arctic and subarctic areas to make the mat thick enough to prevent frost penetra- tion or heave in underlying frost-susceptible materials, particularly when the mat is well-drained. The magnitude of heave may be substantially reduced by the surcharge effect of the weight of the gravel and the structure load in the case of granular pad tovier foundations. Other foundation designs are available to minimize or eliminate the need for non-frost susceptible mat materials, e.g., non-frost-susceptible founda- tion with footings below the frost line, pile foundations, crib founda- tions. In permafrost areas the same annual frost zone phenomena occur. T/L structures in these areas may be either supported on top of the annual frost zone or supported in the underlying permafrost zone, using piles or other means to transmit structure loads through the annual frost-zone. Whenever possible, such structures should be located on clean, non-frost susceptible sand or gravel deposits or rock which are “free of ground ice or of excess intersitial ice which would make the foundation susceptible to settlement on thaw. Such sites are ideal and should be sought whenever possible. For permafrost soils and rock containing excess ice, foundation design should consider maintenance of a stable thermal regime or accept- ance of thermal regime changes. The first concept is applicable in both the continuous and discontinuous permafrost zones. Foundation materials thawed in the summer are completely refrozen the following winter; pro- gressive annual lowering of the permafrost table, thawing of the ice in the ground and settlement is prevented. Permafrost temperatures are not allowed to exceed limits for safe foundation support. - In the case of the acceptance of thermal regime changes, also applicable for both continuous and discontinuous permafrost zones, settlement and other consequences of permafrost degradation caused by the construction and use of the facility are antitipated and accepted or allowed for. Possibility of environmental impact should be considered. Anchorages Anchorages in frozen ground is a difficult and challenging problem because of the tendency for anchors to yield and creep when anchoring in a frozen soil and also because of frost heave forces within the annual frost zone. Although anchors in frozen soil may be capable of sustaining relatively high, short duration loads, they can exhibit unacceptable yield and creep under much lower long term loadings. This is most pronounced when frozen ground temperatures are only slightly below the freezing point as is generally the case in the discontinuous or marginal permafrost areas. Anchor design in soils has been to a large extent empirical. Some theoretical work has been done by investigators to develop data from small- scale. laboratory tests and some controlled full-scale field tests. The design capacities for the various sizes and shapes of commercial anchors are published in various handbook tables or manufactures literature for a range of unfrozen soils. Generally, "pull tests" are recommended during construction to verify design capacities. Design capacity data should be reduced by 75 percent for anchors in thawed soil above permafrost. Unless tt protected in the annual frost zone by anti-heave devices or treated back- fill, all anchors embedded in permafrost should be designed so that the anchor rod is capable of resisting 60 psi of frost thrust which will be in the annual frost layer and a total frost uplift force should be com- puted by assuming the average of 40 psi acting over the depth of the f= annual frost zone. The latter should be added to the design tensile load imposed on the anchor. Generally provision is recommended for _ adjustment of guy line tension in summer and winter.* For permanent anchors in frozen ground, design is based on whichever is controlling: ultimate strength or creep within acceptable limits with appropriate factors of safety -- at least equivalent to the factor of safety in the supported structure based on ultimate strength. ‘Weather Data Table I contains available weather-data pertinent to the T/L route. Records collected by the National Oceanic and Atmospheric Administration (NOAA) and the USAF Air Weather Service (AWS) are the source of most of the data. Relatively little wind information has been collected in Alaska and that available lacks continuity, based on generalized. observations and not compatible as a whole. Unfortunately, wind data for the listed stations is unavailable. ANSI Standard A58.1-1972 contains maps of Alaska overlaid with lines of constant wind speed for mean occurrence intervals of 25, 50 and 100 years. These lines are high relative to the fastest mile (the fastest mile is defined as the fastest mile of wind to pass an anemometer) statistical information available at individual stations. TABLE I** Station Elevation Temperature 9F. | Precipitation, inches —_ aft Abs. | Mean | Abs. 24 hr. jeearly Yearly min. | ann. | max. max. max. mean Valdez 49 -28 | 36 | 87 5.1 83.4 | 59.3 Thompson Pass . 2500 -39 | 28.5} 75 6.6 - 80.5 Tsaina Lodge 1650 -46 | 25.8] 83 Zod - L322, Ernestine 1836 -48 | 26.7} 85 - 18.1 14.4 Tonsina Lodge 1500 -61 | 25.7 | 90 2.5 - 12.6 Willow Lake 1400 -56 | 24.6] 90 - 20.8 13.6 Copper Ctr. 1000 -74 | 25.9} 96 1.3 . 9.7 Copper Valley Sch. 1030 -62 | 27.0 88 — 1053= 10.1 Glennallen 1456 -60 | 24.2 90 1.0 Hes SEZ ** Data from CRREL Draft Report (1980) Design Data for Construction in Alaska. * Linell, K. A., and Lobacz, E. F., (1980), Design and Construction of Founda- oa in Areas of Deep Seasonal Frost and Permafrost, USA CRREL Sp. Report 0-34. This built-in safety factor was applied to account for the significant local variations known to exist in Alaska and the meager amount of wind information available. Table II presents basic wind speed (mph) for these three year mean recurrence intervals for the T/L. -TABLE II Approximate Range of Recurrence Interval = , Basic Wind Speed (mph) 25 year mean . / 90 - 60 50 year mean 100 - 60 100 year mean 100 - 60 It is of interest to note that the power line from Snettisham to Juneau was downed by ice and wind along Salisbury Ridge where gusts ex- ceeding 200 mph were subsequently measured by the Alaska District of the Corps of Engineers. Published information are unknown for the T/L route relative to icing conditions, sleet storms or hoar frost. The precipitation tabulation in Table I is self-explanatory. Snow fall is extremely low in Arctic Alaska but among the highest in the world . in the southern coastal mountains, and moderate in the regions in between. For example, Thompson Pass has recorded up to 225 inches in a single month, whereas at Gulkana, the mean annual snowfall is about 50 inches. Design Freezing and Thawing Indices These indices are used to calculate the depth of ground freezing in the winter and the depth of thaw during the summer, respectively. For design of foundations for average permanent structures, the design freez- ing index is computed for the coldest winter in 30 years of record or is estimated to correspond with this frequency if the number of years of record is limited. Periods of record should be the latest available. The design thawing index is computed on the same frequency and other bases as the design freezing index, except that summer thaw conditions are used. Isolines of these indices are available for Alaska (see reference for Table I or footnote reference below). The design freezing index for the Solomon Gulch-Glennallen T/L ranges from about 2000 to 5000 degree days F, and the design thawing S index on about 4000 to 3500. . s Depth To and Thickness Of Permafrost The depth to the permafrost table depends primarily on the magnitude of air thawing index, the amount of solar radiation that reaches the surface, Hartman, C. W., and Johnson, P. R., (1978), Environmental Atlas of Alaska, University of Alaska, Institute of Water Resources. aes cre at a a ee oo re - eR A Aleyeska. ; : j . the surface cover conditions that existed the past several years, the water content and dry unit weight of the soil. For example, the dapth to surface of permafrost layer in a subarctic region having a mean annual temperature of 26°F, a mean thawing index of 3200 degree days, F, anda treeless area with 6-inch thick moss cover over a Siltsoil (water content 30-40%) would be 5-6 feet. - The thickness of permafrost generally increases with increasing latitude being greater in arctic than subarctic regions. Observed depths in Barrow are about 1300 feet (Arctic) whereas in Fairbanks (Subarctic) about 180 feet. The Solomon Gulch-Glennallen T/L is in the Subarctic. The 1965 Perma- frost Map of Alaska, compiled by 0. J. Ferrians and published by U.S. j Geological Survey as Map 1-445, indicates the following generalized dis- tribution of permafrost along the T/L: Valdez Aréa - Generally free of permafrost; a few small isolated masses of permafrost occur at high elevations and in lowland areas where ground in- sulation is high and ground insolation is low, especially near the border of the permafrost region. Thompson Pass-Tonsina Area - Generally underlain by isolated masses of permafrost. Tonsina-Glennallen Area - Generally underlain by ~— moderately thick to thin permafrost; areas of predominately fine-grained deposits. Maximum determined depth to base of permafrost is about 600 feet. Locally in close proximity to large water bodies, permafrost is absent. Also be- tween’ about Copper Ctr. and Glennallen there are numerous isolated masses of permafrost; areas of predominately coarse-grained deposits. Maximum determined depth to base of permafrost is about 265 feet. In the Copper River Basin and along the North flank of the Alaskan Range extensive areas are free of permafrost. In the vicinity of Thompson Pass and Tiekel borings indicated absence of permafrost and about 35 and 25 feet of unfrozen material, respectively. Sub- surface explorations were conducted in conjunction with the design ad con- struction of Aleyeska oi] pipe line (the T/L essentially parallels this Tine); however, these data are unavailable for use without the prior approval of Seismic Activity* It is noted that the T/L route is considered to be subject to the following maximum probable earthquakes -- from Glennallen to Willow Lake, *Open file reports, (1971), Preliminary Engineering Geologic Maps of the Proposed Trans-Alaska Pipeline Route, USDI, Geologic Survey. Valdez and Gulkana Quadrangles complied by 0. J. Ferrians, Jr. ay Ritcher magnitude 7.0; from Willow Lake to Valdez Ritcher magnitude 8.5. Field Inspection Four tower structures were visited on 6 August 1981 by the Team to observe the as-built structures and better visualize the reported prob- lems. The structures visited were 67-6, 68-1, 68-2 and 79-3. R. W. Retherford only visited Tower 67-6. The T/L was overflown by helicopter from Meals substation (marginal weather) to about Tonsina Camp (clear weather beyond Thompson Pass). Before proceeding to structure 67-6, brief discussions were held with Kenneth R. Alles, Resident Engineer, (M & M), and several of his associates at the Tsaina Lodge field office to obtain background information and availability of design and construc- | tion data. Mr. Alles informed the Team that direct soil explorations ~ and tests were not conducted by (M & M) for design/construction of the . T/L. It was the intent of CVEA that (M & M) utilize Aleyeska data. Field “pull testing” of anchors were not conducted. As-built drawings for Phase I of the contract, in the process of finalization, were briefly examined. Mr. Alles discussed the anchorage problem at structure 67-6, the conductor tensioning problem between structures 68-1 and 68-2, and the vibration problem at structure 79-3. The contractor (Hardline/Myers) used a Hi- Ram 88 vibratory hammer for installation of H-piles for tower foundations and anchorages under Phase I. Driving records were at CVEA Headquarters in Glennallen. i Structure 67-6 (Station 2494 + 31.9). This was designed as a 3-pole, deadend, steel structure, 75 feet high, and fully guyed with a total of 13-TA 20C anchors at-a bevel of 45°. Design specified the North pole to be embedded 8.5 feet, center pole 13.5 feet, and the South pole 8.5 feet; the embedded portion is coated with 2 coats of coal-tar epoxy cement. Design specified that anchors be installed in a 2-ft. wide, 6 ft-'6 in. deep trench and backfilled. The anchor rod to be I-in. diameter 10 ft. long with an 8-in. min. and 12-in. max. stick up above the ground. Hold- ing power of anchor was indicated as 20,000 ibs. The site is considered to be glacial moraine. Actual embedment of poles and anchors were unknown because as-built drawings had not been finalized. The structure was built in 1980 and after stringing of conductors, seven anchors exhibited unacceptable displacement with accompanying guy wire slack. Anchor rod stick up was estimated to be 2-2% ft. These were the six backside anchors and the bisector anchor. The R. E. reported the _ backside conductors were strung first. Replacement anchors and guy wires were installed subsequently: three each to the backside of each pole and two at the bisector to the north pole. These are referred to as TA-20CR on drawings. The original "failed" anchors remained in place and no evidence was present of ground surface bulging or cracking. Anchor trench backfill material appeared to be a grey-silty-sandy gravel with cobbles/ boulders over the six (6) backside anchors and brownish silty sandy gravel over the bisector anchor. Surficially, the backfill appeared to extend horizontally from the.anchors to the exposed anchor rods and was depressed. During erection of this structure, the project engineer stated about 30- contractor crews were working on Phase I of the contract and an inspector was not present during installation of these anchors. Visually the struc- ture now appeared stable with all tower guys under stress. oo -o- Structure 68-1 (Station 2526 + 09). This was designed as a 3-pole, deadend, steel structure, 50 ft. high and fully guyed with a total of 14-TA-2H grouted rock anchors (2-in. diam. hole) with a minimum rock embedment of 3 feet. The design holding maximum working load is 35,000 lbs. The anchor rod is 1-in. diam. and 12 ft. long. The tower poles are coated with 2 coats of coal-tar epoxy cement. The site is bedrock outcrop, with soil and vegetation in depressions. Actual embedment of poles and anchors were unknown because as-built drawings had not been .finalized. Erection was in 1980. This structure appeared stable with guy wires under stress, al- though some anchor rods did not "line-up" with guy wires. Structure 68-2 (Station 2556 + 44.071). This was designed as a 3-pole, deadend, steel structure, 60 ft. high and fully guyed with a total of 10-TA-2C@anchors as used for structure 67-6. The site is glacial moraine with many surface boulders. The embedded portion of the tower poles were coated with 2 coats of coal-tar epoxy cement. Actual embedment of poles and anchors were unknown because as-built drawings had not been finalized. Erection was in 1980. The structure appeared stable with all guy wires under stress. Inference was made that difficulties were experienced with anchorages during stringing of conductors. Structure 79-3 (Vicinity Pump Station 12). This is a 3-pole, steel tangent structure, designated as ST-15T and fully guyed with a TA-4TR-2 anchor (H-pile, 22-ft. embedment) ahead and back of each pole and a TA- A4TR-1 anchor (H-pile, 12-ft.embedment) guyed to the north and south pole- The 3-poles are cable connected to each other near the top- Each pole is set on a steel H-pile foundation. This structure apparently experienced severe vibrations because of wind and required the addition of angle iron spoilers and additional tower guy wires. Several of the cross guy wires appeared close to each other at their intersection. Reportedly the steel H-pile supporting the north pole had excess stick up and punctured the pole during extreme vibrations. This pole had been repaired with a welded steel patch and the pile cut-off to proper elevation. The site is considered to be glacial moraine. Actual embedment of steel H-piles should appear in the driving records to be obtained from CVEA. Erection was in 1980. The structure appeared stable with all guy wires under stress. Other. During the helicopter overflight it was noted in the vicinity Aleyeska Pipe Line Marker 755, a 3-pole tangent structure was sited on a : bedrock outcrop. The exposed rock face near the south pole had experienced ~ recent slabbing. How near to the structure was unknown from the helicopter. . Discussion of Tower Foundations and Guy Anchors Site data needed for design of foundations in cold regions include the same information as would be required in temperate regions but with addi- tional requirements imposed by the special climatic conditions. Site in- - formation may be summarized as: Climate (General and Local); physiography and geology, including topography and surface cover; subsurface conditions; ground thermal regime; hydrology and drainage; materials of construction; transportation facilities and access; and construction cost factors. Most of this information is also needed to review foundation designs’ for structural adequacy. However, such information was unavailable to properly evaluate tower ' -y- foundations and anchor designs. Frost heave and settlement may be anticipated along the T/L provided the structures are not restrained by countermeasures. The coal-tar epoxy cement applied to the subgrade portion of directly embedded steel poles should reduce frost thrust on these poles. Piling offers many advantages where construction is on frost-suscept- ible foundation soils in areas of deep seasonal frost penetration or perma- frost with high ice content. Pile foundations can be constructed with minimum disturbance to the thermal regime and can isolate the structure from seasonal heave and subsidence movements in the annual frost zone and from at least limited degradation of the permafrost. Structure load is transferred by the pile to depths where soil strength remains relatively stable during the life of the structure. Pile foundations must be designed with sufficient embedment to support by imposed load in adfreeze bond* without objectionable displacement under the warmest ground temperatures expected unless suitable end bearing on ice-free bedrock or other reliable strata can be obtained. The piles must be capable of resisting additional down drag of negative skin friction from consolidating fill or thawed foundation soils, and must provide sufficient anchorage and tensile strength to prevent upward displacement and/or pile structural failure from frost heave forces. Allowable loadings of piles in frozen ground are determined by creep deformation which occurs under steady loadings at stress levels well below the rupture levels measured in ordinary relatively rapid tests to failure. Anchor design in soils has been to a large extent empirical. Design capacities for various sizes and shapes of commercial anchors are published in various handbook tables or manufactures literature for a range of un- frozen soils. Generally "pull-tests” are recommended during construction to verify design capacities. Also, design capacities in cold regions should consider the effects of freeze-thaw in the annual frost zone and anchor burial in permafrost. Recommendations These recommendations are based upon the information presented in this memorandum. . . - North of Thompson Pass absolute minimum temperatures are more severe than the -40°F shown in the 1978 Summary of Basic Design Data. The effect of these colder temperatures should be studied relative to the adequacy of the T/L design. . , The effects of freezing and thawing of foundation materials and the presence of permafrost on the adequacy of tower foundations and anchorage systems should be investigated using current state-of-the-art technology for design of foundations in areas of deep seasonal frost penetration and permafrost. Such a study would depend mainly upon the availability of * Adfreeze bond strengths are directly related to permafrost temperatures. -1JU- subsurface information. The seven "failed" anchors at structure 67-6 should be tested to establish their current holding capacity. Necessary soils data should be obtained for correlation purposes. TA-20C anchors: should be in- stalled at this site in accordance with construction specifications. These anchors should be pull-tested. Two test methods are suggested: One under instantaneous load (after seating) at 100% design load capacity and one, after seating, in steps of 25% of design load capacity until failure. Necessary soils data should be obtained for analysis and correlation. Consideration should be given to pull testing of similar anchors installed in differing foundation materials of the T/L. Consideration should be given to examining the T/L design relative to seismic activity. Pureabenraaaag ear ee oe ~ yeernn nay PRO FET Bay BaWE OBR] Sa any — — pee open py a EIFS PFE GEOTECHNICAL INVESTIGATION OF SOLOMON GULCH - GLENNALLEN 138 KV TRANSMISSION LINE GUY ANCHORS FOR COPPER VALLEY ELECTRIC ASSOCIATION, INC. SEPTEMBER 1981 International Engineering Company, Inc. 180 Howard Street San Francisco, California 94105 Chapter GEOTECHNICAL INVESTIGATION OF SOLOMON GULCH-GLENNALLEN 138 kV TRANSMISSION LINE GUY — ANCHORS SEPTEMBER 1981 TABLE OF CONTENTS INTRODUCTION 1 General 2 Authorization 3 Purpose and Scope -4 Information Sources 5 Report Organization 6 Performance -7 Acknowledgements 1.8 Limitations SITE CONDITIONS & PERFORMANCE OF THE STRUCTURE 2.1 Access to Site 2.2 Soil Conditions 2.3 Description & Performance of the Structure FIELD INVESTIGATIONS 3.1 General . 3.2 Soil Sampling, Installation & Testing of Anchors 3.3 Results of Investigation 3.4 Findings and Discussion 3.5 Conclusions and Recommendations 1-1 1-2 1-2 1-2 1-2 1-3 1-3 2-1 2-1 3-1 3-2 3-4 3-7 4 LABORATORY INVESTIGATION : 4.1 General : 4-1 4.2 Laboratory Test Program & Results 4-1 4.3 Discussion and Conclusions 4-3 5 DESIGN AND ANALYSIS "5.1 General 5-1 5.2 Method of Design and Analysis 5-2 if 5.3 Selection of Parameters for Analysis . 5-5 1 : 5.4 Results of Analysis & Discussion 5-6 ' 5.5 Conclusions 5-8 i 5.6 References 5-10 f t 6 CONCLUSIONS & RECOMMENDATIONS | 6.1 Conclusions 6-1 6.2 Recommendations 6-5 F t : REFERENCES ii ST pee were eee ery Per ewe Peg Table 1-1 3-2 3-3 4-2 5-1 5-5 TABLES Phase I - Investigation Program of 138 kV Transmission Line Anchor Failure Rock and Soil Anchor Data Summary of Pullout Tests on Abandoned Anchors (Type TA-20C) at Structure No. 67-6. ; . Concrete Anchor (Type TA-20C) Pullout Test Data Suggested Laboratory Test Program Investigation of Anchor Failure Summary of Soil Properties at Structure No. 67-6. Summary of Tests and Analysis of Guyed Anchors Including Comments and Recommendations Guide to Bond Stresses for Three Catagories of Rock Chances’ Soil Classification System Density and Shear Strength Parameters for Average Alaska Soil - Results of Survey Anchor Capacities at Four Separate Sites iii wo oe FIGURES Figure 3-1 Location Plan of Test Site 3-2 Sketch Plan Showing Anchors and Trenches at the Location of Structure No. 67-6. 3-3 Sketch Showing IECO Installed Anchor Layout in Trench: Typical Concrete Anchor. Installation Details in Strong Foundation Materials. 3-4 Typical Concrete Anchor Installation Details in Strong Foundation Materials. 3-5 Typical Installation of Abandoned Concrete Anchors at Structure No. 67-6. 3-6 Concrete Anchor Pullout Test Data 4-1 Su vs E for Glacial Till APPENDICES Appendix A Soil Test Report prepared by Alaska Testlab B Anchor Pullout Test Report prepared by Van Gullik & Associates Cc Trip Report of Nani G. Banerjee - September 30, 1982 iv CHAPTER 1 INTRODUCTION 1.1 GENERAL The content of this report is confined to geotechnical investigation of the guy anchors and will form a part of the main report. The Phase-1 study is addressed towards evaluation the adequacy of typical soil anchors as designed and constructed based on limited field and laboratory investigation and office studies. Our conclusions and recommendations, including the need for further investigation to assure the safety of the structures, will also form part of this report. This report was concluded without specific field check on rock anchors because of time restraints. A supplementary report commenting on rock Peat Bast waa Banteay waaay aay peer ewory BR anchors and other observed installations along the line is included as Appendix C. : 1-1 roe | YC CR ‘oarnannamnentn cnet a en cnet a: eee RE RTT —— — — SRR SEAR, new RAY ERS Bray par qaaay pxeeany Perey Prem were oo —y =_y meQ omy | ETE 1.2 AUTHORIZATION The investigation covered in this report is part of the extended Stage-1 study authorized on July 21, 1981 by the CVEA Board of Directors. 1.3 PURPOSE AND SCOPE The purpose of the work described in this report is design review of guy - anchors based on field and laboratory investigation, including anchor pull-out tests, and office studies at selected locations. Major activities involved in analyzing the design capacity and “as built” capacity of anchors including workmanship are included in Table 1-1. 1.4 INFORMATION SOURCES In addition to the data and documents provided by CVEA, Miner and !tiner Inc., various agencies of the U.S. Government (USBR, DOA-REA etc.) also generously assisted us with data, documents and information relevant to this study. The information sources are recorded in file but not repeated here for the sake of brevity. 1.5 REPORT ORGANIZATION This report consists of the main text in six chapters and the basic data in two appendices. The introduction is contained in Chapter 1, and the site condition and performance of structure are included in Chapter 2. Details of field exploration program, methodology and results are presented in Chapter 3. In chapter 4 laboratory tests performed and results obtained are briefly reviewed. In Chapter 5, state-of-the-art of soil and rock anchors designs are briefly reviewed; method of analysis including the selection of design parameters are briefly described and results presented. Conclusions and recommenda- tions are included in Chapter 6. Fercorg ree romeo, pprecrreeg mee pomee Pe Fe pe 1.6 PERFORMANCE The study team consists of the following members, however the extent of their involvement varies from few hours per week to full time. Personnel: R. W. Retherford D. Steeby E. F. Lobacz - Outside Consultant R. P. Valaitis G. I. Israelson T. R. Wathen C. E. Buckles N. G. Banerjee Field Anchor Pull-out Tests and Laboratory testing were carried out, under subcontracts, respectively by Van Gullik & Associates, Anchorage and DOWL Engineering/Alaska Testlab, Anchorage, Alaska. 1.7 ACKNOWLEDGEMENTS International Engineering Company, Inc. is grateful to the management and staff of the Coppper Valley Electric Association, Inc., in particular to Mr. Jim Palin for providing information included in this report and for their very active cooperation and participation in the realization of this study. Our grateful appreciation also goes to the management and staff of Miner and Miner, Inc. for providing various data and documents required for this study. ee een roe weoteeg =a eS ae Le = es 1.8 LIMITATIONS Soil deposits and rock formations may vary in type, strength, and many other important properties between trenches, and many other points of examination. The analyses that we have made assume that the data determined in the field and laboratory are reasonably representative of field conditions and that the subsurface conditions are reasonably susceptible to interpolation and extrapolation between locations of subsurface exploration. The investigations for 138 kV¥ Transmission Line were made as extensive and intensive as considered practical, with due consideration to the physical aspects of the site and the justifiable and available techniques and budget. The conclusions contained in this report are based on our professional judgement and experience, using data obtained from the site and laboratory investigations. We have analyzed the available information using what we believe to be the most applicable engineering approaches that are available to the profession at this time. eres, ay prewey nore yoo ont ers ee Gg pm gg gee Ry PHASE I Phase Stage TABLE 1-1 PROGRAM OF INVESTIGATION OF 138 kV TRANSMISSION LINE ANCHOR FAILURE Activity Purpose I I I II III Review. of available data. Reconnaissance survey of site. Perform pullout tests on abandoned anchors at Structure 67-6. Dig several trenches at the location of aban- doned anchors. Install anchors and perform pullout tests. Write interim report Laboratory test program Office studies. Phase I Final Report Define the nature of problem. Plan and develop program of exploration. Determine residual capacity, observe failure mechanism and record movement with load/ time. Complete logging of trench. ° Record failure plane and mechanism. Check alignment of anchors. Collect disturbed and undis- turbed samples for labora- tory testing. Determine deformation every 5 kips load increment and ultimate capacity. Determine deformation due to creep. Appraise findings from field program. Soil identification and char- acterize materials for ana- lytical use. Compare computed anchor capa- city with that from field pullout tests. Document results of investi- gation. . Provide conclusions and recommendations. If Phase I program is inconclusive, develop a Phase II program of investigation. eo Pe pe Ge pene menus ae py yaa eR >| Cp Oe ere mre CHAPTER 2 SITE CONDITIONS AND PERFORMANCE OF THE SOIL ANCHORS 2.1 ACCESS TO SITE The Solomon Gulch - Glennallen 138 kV Transmission Line extends from Glennallen to Valdez (see Figure 3-1) and essentially runs parallel to Aleyeska oi] pipeline; thus, no serious problem exists for access to the transmission tower sites. 2.2 SOIL CONDITIONS The transmission line covers an extended area; thus, a variety of foundation conditions could possibly exist. Site specific soils exploration and testing were not conducted along the transmission line during the design and construction phase.* Subsurface soils information along the transmission line is limited to information recovered during the current field investigation at Structure 67-6, described below, and from information obtained from the soil investigation performed by R& Consultants, Inc. at pump stations 11 and 12. The field investigation at pump station 11 revealed the following subsurface conditions: the site is underlain by thick permafrost to the depth of drilling. The underlying soil profile typically consists of silt with some organic debris intermixed to 3.5 feet below the ground surface. Beneath this is a layer of sand with varying amounts of silt, gravel and clay to a depth of approximately 5 feet followed by a silt or silty clay with varying amounts of sand to 12 feet. Below 12 feet in depth, a clay with trace of silt was encountered to the depth of drilling, 40 feet. *Subsurface data as mapped by Alyeska along the Pipeline route paralleled by the transmission line was included by Miner and Miner on the plans for for line. Zi PoKRg paensg pong, ny erence — FE GWE 3 om ny mag of Fy BE PR oY EG At pump station 12, the following subsurface conditions were encountered: The site is underlain by permafrost ranging from 20 to 21.5 feet in depth. The soil profile typically consists of silt with varying amounts of sand to 18 feet followed by sand with trace to some silt to 26 feet in depth. Beneath this zone, a silt with trace sand was encountered to the depth of drilling, 35.5 feet. During the field investigation at Structure 67-6, the following subsurface conditions were encountered in the test pits: a layer of dark brown organics varying in thickness from 4 to 6 inches is underlain by a layer of tan, sandy, gravelly silt varying from 1.0 to 2.0 feet thick. Below a depth of approximately 2.0 feet is very dense, well cemented glacial till, consisting of sandy silty gravel. No permafrost was encountered at the site and no ice lenses were visible in the soil. According to the United States Geological Survey Permafrost Map 1-445, the transmission line traverses regions generally free of permafrost in the Valdez area, underlain by isolated masses of permafrost in the mountainous areas from Thompson Pass to Tonsina, and underlain by moderately thick to thin permafrost or numerous isolated masses of permafrost in the lowland and upland areas from Tonsina to Glennallen. 2.3 DESCRIPTION AND PERFORMANCE OF SOIL ANICHORS The transmission tower 67-6 was designed as a 3-pole, deadend tubular steel Structure. The structure is 75 feet high and fully guyed with 13 TA-20C anchors at a design inclination of 45°. The holding power of the anchors was indicated as 20,000 Ibs. The structure was built in 1980. During substantial completion level inspection, failure of some anchors near structure 67-6 and twenty other locations came to light. Anchors had moved by about 2 feet causing loss of tension of the guy wires and 2-2 tilting of the towers. The failed anchors remained in place and field investigations indicated no evidence of ground surface bulging or cracking. Replacement anchors and guy wires were subsequently installed at structure 67-6, referred to as TA-20CR. Visual inspection of the structure indicates that it is stable with all tower guys under - stress. ——— — = — poe Cy. eS es ee ms 3.1 CHAPTER 3 FIELD INVESTIGATION GENERAL Location of the test site selected for Phase 1 field investigation is shown in Figure 3-1. Structure No. 67-6 was selected as the test site because at this location seven of the concrete anchors (type TA-20C) were abandoned and replaced by twin type concrete anchors designated TA-20CR. This structure was designed as a three-pole, dead-end, steel structure 75 feet high and fully guyed with a total of 13 TA-20C soil anchors inclined at 45° according to Specification drawing. Particulars of the soil anchors specified for this job are included in Table 3-1. Since all the failed anchors at Structure No. 67-6 were abandoned, a thorough field investigation at this site was considered possible for evaluating the causes of anchor failure without interfering with the performance of the structure including the anchors in service. Nos. 1 through 7 are shown in Fig 3-2. exploration and testing was executed from 9:30 a.m. to 8:30 p.m. on The layout of the abandoned anchors arbitrarily designated A rush program of site August 13, 1981, with the following participants: oO Jim Finley, DOWL Engineering/Alaska Testlab Anchorage, Alaska Burke Wick, assisted by Nat & Lynn, Van Gullik & Assoc., Anchorage, Alaska Copper Valley Corporation: Dale Steeby, IECO, Anchorage Logging of Trenches and Disturbed and Undisturbed Soil Sampling Performed Pullout Tests on Abandoned Anchors and Newly Installed Test Anchor Provided Backhoe and Operator Field Investigation Program Coordinator oan eat | gap pea PO pO guy eg pie ol Nani Banerjee, IECO, Test Program Review, Data Evalua- San Francisco tion and Supervision of Sampling and Testing a Ken Alles, RE, Miner & Miner Observer Consulting Engineers, Inc. Chief Engineer, ITT Meyer Eng. Observer 3.2 SOIL SAMPLING, INSTALLATION AND TESTING OF ANCHORS A. Soil Sampling Two trenches were dug at the location of abandoned anchors No. 1 and No. 4 (Fig 3-2) with a backhoe. The trenches were dug close enough to the anchors for physical verification of the orientation of the anchors, its depth of embedment, inclination of the anchor rod to the horizontal, and examination and sampling of soil in the vicinity of the anchors. Jim Finley of DOWL Engineering/Alaska Testlab logged the trenches and also collected disturbed and undisturbed samples of - backfill material for laboratory tests. Attempts to collect undisturbed samples of glacial till material was unsuccessful, the in-situ material being hard, dense, cemented, and mixed with cobbles and boulders. Additional details of soil sampling in trenches could be seen in Appendix-A. Anchor No. 1 was retrieved for installing it as a test anchor in another trench. B. Installation of Test Anchor The test anchor was installed essentially according to Miner and Miner's anchor drawing to check what could have been the capacity of anchor type TA-20C at this site had the installation been done i according to their drawing and Specification. = —— 4 oe rome pene ye ere awn coy a ery Pm pe RY The location of the test anchor is shown in Figure 3-2. For installing the test anchor a 2.5-foot-wide main trench was dug with a backhoe to a maximum depth of 6.5 to 7.0 feet. A narrow slot inclined 45° with the horizontal was cut manually with hand tools on one of. the vertical trench walls. Abandoned concrete anchor No. 1 reclaimed from underground by digging a trench was installed in the new trench as the test anchor. In the installed position the concrete button of the anchor was wedged against the undisturbed trench wall, with the anchor rod lodged in the narrow slot inclined 45° with the horizontal as indicated in the Specification. The trench was then backfilled with the excavated material from the trench, by compacting it in layers manually with rammers as well as with the bucket of the backhoe. The trench cut was long enough to instal] two anchors, however, very inclement weather conditions permitted installation and testing of one test anchor only. View of the anchor assembly in the trench is shown in Figure 3-3. The workmanship of the installed anchors is rated as average and should be considered easily attainable during ~_ construction. For the same type of anchor (TA-20C) we believe significantly higher capacity is achievable at this site if the Contractor ‘had installed the anchors strictly in accordance with the original specifications provided by Copper Valley Electric Association as prepared by their Engineer, Miner and Miner. C. Anchor Pullout Tests Five of the abandoned concrete anchors Type TA-20C arbitrarily designated as Nos. 1, 3, 5, 6 and.7 (Fig 3-2) were subjected to pullout tests to determine their residual ultimate load capacity. A special test set up consisting of 60-ton capacity hydraulic jack mounted on a special aluminum frame with widely spaced feet was used for the anchor pullout tests. Van Gullik & Associates has used this equipment for proof testing of anchors for a number of transmission line systems. Each leg of the frame is seated on an approximately 2" x 3' base, thus the total reactive load is distributed over a large surface area ww eel Po oo ery | (==24 sq. ft.), resulting in low intensity of loading and minimal settlement of the frame. Since the bases are not rigidly connected to the legs, the bases have freedom to rock and adjust to the ground surface. The frame was also tied to one of the transmission poles to avoid its sliding while performing the pullout tests. A measuring scale was mounted along the anchor rod, and held in position with a C-clamp. A steel wire or thread mounted on two independent posts set inside the ground, was run across the anchor rod but over the measuring scale, served as the datum line for measuring movement of the anchor rod during pullout tests. For pullout test on each anchor, load was applied in 5-kips increments, and movement of the anchor rod was recorded at five minute intervals up to a maximum period of 15 minutes after each load increment. For measuring anchor rod movement due to creep in soil, constant pull was maintained by pumping fluid at each stage of loading. Each anchor was loaded to its ultimate residual capacity. It must be mentioned that, for the abandoned anchors, 1-5 to 3 feet length of anchor rod was exposed above the ground before starting the pullout test against 8 to 12 inches provided in the Specification. This shows that the anchors were subjected in the past to loads large enough to cause failure associated with large movement of anchors. Therefore, loads applied during the current test program are a measure of the abandoned anchors’ residual capacity. Pull-out test was performed for the anchor reinstalled by IECO following the same method as adopted for the abandoned anchors described above. : 3.3 RESULTS OF INVESTIGATION Results of field and laboratory investigation are contained in two basic reports included as Appendix A and B of this report. Soil Report prepared by DOWL Engineering/Alaska Testlab includes detailed log of trenches near anchors and field and laboratory soil test data (Appendix A). weeny aes rere gewrow pemeng feaoy paneae yee pany A report on the anchor pullout tests performed by Van Gullik & Associates is included as Appendix B. However, investigation data in brief summary form are included in the text. In Figure 3-5 typical layout of the abandoned anchors are shown. Anchor pullout tests data in summary form are included in Table 3-2 and 3-3, respectively, for the abandoned anchors and the reinstalled anchor. In Figure 3-6 movements of reinstalled anchor for 5-kips load increments are shown. In the same figure (Fig 3-6) movements of the abandoned anchors for the maximum applied load are shown. Plot of load versus movement of each anchor for 5-kips load increments are included in Appendix B. 3.4 FINDINGS AND DISCUSSION A. The soil condition at the site of Structure No. 67-6 is considered well above average since the glacial till in which the anchors are founded, is dense, hard, well-cemented, and strong in in-situ conditions and above the ground water table. B. From two trenches opened at the location of abandoned anchor No. 1 and No. 4, the workmanship is rated as poor and the anchor installation unsatisfactory due to the following reasons: 1. Very loose and soft soil in the trench indicated very little or no compaction of the backfill. 2. Trenches were not formed well to take full advantage of the high shear resistance of the undistrubed in-situ cemented material (glacial till). Neither the concrete anchor appears to have been wedged against the undisturbed trench wall, nor the anchor rod laid in a narrow slot cut and sloped 45° with : the horizontal. oe Bee eg os Hewes Benen, pamennry muy pans Lean | moog mr wry ray manag weancgg 3. The anchors were buried in loose backfill material in the trench with steeper pull angles with the horizontal (55° to 56.5°) than that specified (8=45°). Consequently the anchor, as installed, were subjected to a significantly higher ‘pull for the same line load and lower passive resistance of the loose backfill compared to that of a properly installed anchor inclined at 45° with the horizontal. Before the pullout tests on abandoned anchors Nos. 1, 3, 5, 6 and 7, 1.5 - 3.0 ft. lengths of anchor rods were exposed above the ground aginst 8 - 12 inch specified. It indicates that the anchors were presumably subjected in the past to loads high enough to cause failure or pullout associated with large movement close to a foot and above. Therefore, the actual load which caused the failure and movement had to be ascertained during further investigation. The theoretical capacity of anchors are also computed by using the shear strength parameters of loose backfill material as determined from laboratory tests and discussed in Chapter 5. For the abandoned anchors (Nos. 1, 3, 5, 6 and 7), the pullout test load in the range of 12 to 15 kips for assumed allowable movement of 2-inches reflect the anchors residual capacity and not their capacity as installed. Pullout test results of the test anchor installed by IECO according to M & M drawing and Specification, and representing average workmanship shows that for Type TA-20C concrete anchor, maximum short term load of 23,000 pounds is attainable with 2-inch anchor movement for well above average soil conditions (glacial till) at Structure No. 67-6. However, these tests are not adequate to define its long term load capacity which is most critical for guyed anchors. If this anchor can hold 23,000 pounds load for 24 hours with no more than 5% loss of load, its safe long term load capacity could be rated as 16,000 pounds. penny area Coed — oy | OE Kurang Poa men oma ‘ama ar Ea 3.0) It is considered important that field tests of installed anchors be performed at sufficient locations to assure con- fidence in anticipated performance. Future construction work should include provisions for such "proof" tests as part of the construction work.. Anchor placement techniques have decisive influence on the behavior of anchors. With anchor installation method detailed in Fig 3-4, significantly higher anchor capacity would be achievable in glacial till as encountered in Structure 67-6. CONCLUSIONS AND RECOMMENDATIONS The field investigation of structure 67-6 established that an installation of the TA-20C anchor done in accordance with the original specifications would develop the rated holding power indicated. The field investigation also showed clearly that poor work- manship contributed to the failures of the original TA-20C anchors at the 67-6 structure site. The field investigation showed that the original anchor locations were such that guy angles greater than 45° (see Figure 3-5) existed which would produce correspondingly greater loads. This factor contributed to the anchor failures at this location. CVEA's soil anchor type TA-20C would be considered to have a safe long and short term load capacities of 16,000 pounds and 23,000 pounds respectively if installed in glacial tills in accordance with the industry practices reflected in the REA specifications. TABLE 3-1 ROCK AND SOIL ANCHOR DATA rer Teraerag Wiese ad Maximum Working Anchor Anchor Load Designation Anchor Spec. Type Description (ibs) Remarks TA-2H CYEA Spec. Rock j-inch diam. anchor 35,000 Anchor rod, grouted inside 2-inch diam. in- clined hole (45°) inside rock; 3-ft min. length of embedment in rock with an anchor nut at the end. Weeweary, Rema Pens noone awn TA-10C CYEA Spec. Concrete From 12-inch diam. 10,000 Holding power in Anchor tapered to 6-inch ordinary soil. diam.; 3/4-inch voy i diam, 9-ft long anchor rod. Hl TA-20C CVEA Spec. Concrete From 18-inch diam. 20,000 Holding power in » Anchor tapered to 6-inch ordinary soil. i diam.; 1l-inch diam. a 10-ft long anchor H rod. f TA-20CR* CVYEA Spec. Concrete 7-foot, twin rod -Modified new ; anchors installed F at structure 67-6. * Do not have complete details of this anchor at this time. | ener ct EE PR te tii ee =a wees Sry woowrey een -——4 oe | Anchor No. 1 3 o Notes: 1. TABLE 3-2 SUMMARY OF PULL-OUT TESTS ON ABANDONED ANCHOR (TYPE TA-20C) AT STRUCTURE 67-6 Maximum Load, Kips 12 7 19 15 19 Movement (inches) 2.44 4.56 3.94 4.25 8.9 Remarks For each anchor, the load shown is the maximum which could be developed during the pullout test on August 15, 1981. This table provides a summary of the results of pull-out tests performed on abandoned anchors at Structure 67-6. A complete report is included on Appendix B. At the time of the pull-out tests on August 15, 1981, 2 to 3 ft. length of the anchor rods were exposed above the ground which are indicative of the anchors having failed under the applied toad earlier. TABLE 3-3 CONCRETE ANCHOR (TYPE-TA-20C ) PULL-OUT TEST DATA ANCHOR INSTALLED BY: _IECO DATE OF INSTALLATION & TESTING: 8/15/81 LOCATION: AT STRUCTURE NO. 67-6 ow g Teng Dial Cumulative Load, Clock Time Recording Movement Kips (pm) (inches ) (inches ) Remarks 0 6:15 6-11/16 0 5 6:16 6-5/16 0.375 5 6:21 6-5/16 0.375 5 6:26 6-5/16 0.375 10 6:27 6 0.688 10 6:32 6 0.688 10 6:37 6 0.688 15 6:38 5-9/16 1.125 15 6:43 5-9/16 1.125 15 6:48 5-9/16 1.125 20 6:49 5-3/16 1.50 20 6:54 5-2/16 1.563 20 6:59 5-1/16 1.625 25 720 4-8/16 2.183 25 7:05 4-8/16 2.183 25 7:10 4-8/16 2.187 30 Ce 4-4/16 2.438 30 7:16 4-4/16 2.438 30 7:21 4-4/16 2.438 35 7:23 3-11/16 3.0 35 7:28 3-8/16 3.188 35 - 7233 3-8/16 3.188 40 7:35 1 5.68 Notes: 1. Ze Tests performed and data recorded by Van Gullik & Associates under IECO's supervision. A complete test report will be submitted by Van Gullik & Associates in due course. Seta, AT AND, AND WRbeEL WHT COURLLS AMO BORIC RE TALUY AnO TALI, EDR S SHIGE rs SF, Se eee) ee woo toate ab [ fosep gage ge apinal tees se hee meee Span eae |e wale we wete Coren WULEY tAKeTRe MISDEHTION. We t|L > SDCONON FUL 3 5 (RIT meaner PAL ietan ee 9 sn, eee mater of = FIGURE NO.31 : LOCATION PLAN CF TEST SITE CSTHUCTBEE 47-6) _—" ey lkeolelaltnigith . ee TRUCICKL CFC | YAncHge INSTALLE OF TESTED BY L=CO ON ©7158) i hes hy Et EY @) Shows Soccton of abandmed anchors Trench ong Aor sor/ s ampling ¢ tPSpectran of «cbandoned GWrchher 777.51 fer- ii Anchor ynstalied ane! Saenacs by ZECO on B//5/8/. EHES FB JE, £00 Eye will Sil v 40,000 Jbs Pa “Zz [ne&ee ZFIG.3-2 SKETCH PLAN SHOWING ANCHORS F TRENCHES wt AT THE LOCATION OF STRUCTURE NO. BF -S pn Bea poem REY pomeny ery peng prweny emmy meme fF NCI6R kom i= (INCH Dnt. whiz ji: eb 3 aad Baie asd, = | ! = bp th + NOTE: 1 TRIRTINA YS Bae Fit TSN Tf OOS 2 THE WORKMANSHIP "1 comencreD ¥ IN-SITU SE” ile FOR WSTHLLING TEST: “Keay anteane / , CLMEIde THE: (ceayEy SUT Karey "ANCHOR SHOULD BE CONSIDERED .,: ight. | OBBLES ¢ GRAVELS, £ BOULLERS) TO REPRESENT AVERAGE QUALITY 2 mca dt Piao HARD F¢:CEMENTED~ NOT THE BEST ATTAINABLE. 6 ero “CONCRETE ANCHOR, TYPE TA:20 © LURING CONSTRUCTION » | = i | | -1B'IN. DIN, WITH ANCHOR ROD aa HIMES HASSE a oA re é DZS MeN ey oe . . . is < a Sa 7 |! - i 7 ee, "PLAN. eee ey i FIG ~ BBiskerei/) SHOWING UECO. INSTALLED" lowed nneitop ne LAYOUT: IN TRE ENCH 388 iv eri | , mh SRNR TN ch A LN SR EE I enn hn RR RRA Ah nnn sn NOAM pres pow he LAB 0 wt Shots. € cepa eet IE: NTR poyprerenwem in TYEIEA { 4 CONCRETE ANCHOR ANSTALLATION DETAILS STRONG FOUNDATION MATERIALS : peor Berry pmwerg Anemone, eg ste (PREFERABLY DIG ROUND PosT HOLE FOR ANCHOR. {altace daa OK WITH A BASIC HCE » 1-UNCH DIET, LOFT gr ZENG ANCHOR Lob ~ yt LIMDISTURBLD Sole. (QLNCINE The) PENSE , HARD F CEMEVITED IN UNDISTURBED CONDITION CONCRETE ANCHOR 18-INCH DIOMETER ! pier \t iy te yore CHANNEL FOR INSTALLING ANCHCR ROD INCLIVED 45° WITH THE HORIZONTAL + XY : v . ——s = 7 oe = 1 NOTES 4 Lrstall Concrete oncher on verheal bevd ho Or.trench such that the anchor pulls eg2irst wendss ter bed arth (Grea Tih ad Structure 2. ince reut the verheal wot at the cpratred a so that the oncher could be instotled Cuttin: against the undisturbed card) at right Ong ‘0 the gy wre. 3A narrow Ce"wroe) channel should be ot Clyer w trenching tool creirittedd with a small povwry a $0 thet She rod ceuld be inecfalied inet neds 4 With tae biort ental. 4. Both ancher eurl aneber veel tianeh ee fei, should be back- hited by Lamping vn OyeTs 6-9-1nch thith, so that te Chnydacteer ‘mar AMES @ minimum yelsrrve fnypre tea 15, compared WASTAL = DISS 7, 6, Wale seating Mie conerete Anthiy Care Mint taken tovemeve all loose materials tran the wuekreuk area 50 Mot the en'e ef the co batten pigntty sits ogyaingd the Uudistarte carth surface. 6 the backfill serfece shel be Suchet tea dhe original grand ninface 0d sholdly fo ensure guitle nurface chainane aud’ thu preven Y the Sormatier pol petes Ov pid 1m Seketeet sri} fee tram evganie meteriols shu | be Uned a bnrerfiH. 8: Plan yee sheuld be Shown en congtruchan ' Arcwngs Han vier 18 nek shen here inter | Since He chewing “& Pryier goss 1% an i evoviple \ I NoTes, 4, CONFIGURATION OF ABANDONED ANCHOR TRENCH SHOWN (§ APPROXIMIATE . 2 CYLINDRICAL SHEAR SYRFACE DEVELOPED EN7/RELY IN LOOSE BACK-FILL MATERIAL WAS . VISIBLE IN TRENCHES OPENED AT ANCHOR #H1IFH4-. 3. ABANOOND ANCHORS WERE INSTALLED ATA MUCH STEEPER ANGLE (sS°~ 58'5°) THAN Pane 45°) PROVIDED Iv THE DRAWING. THE SLOPE OF THE ANCHORS WERE MEASURED BY (NCLINOMETERS AND ALSO VERIF/ED FRON HETGHT . OF POLE AND DISTANCE” BETWEEN ANCHOR AND POLE» (AS INSTALLED" AS SPECIFIED 3,NEWLY (NS7TALLED ANCHORS ARE& /NCLINED AT ABOUT 48° WITH ZHE HORI2ONTAL (NCT SHOWN HERE) - /N ANCHOR 4 S0/L CLASSIFICATIONS ARE BASED ON VISUAL OBSERVATION IN THE F/ELD. fie tl VERY, LOOSE, ; SOFT, UNOMPACTED BACKs Filed. CLAYEY SILT /SILTY CLAY (sC-0t) , FIG, BS TYPILAL INSTALLATION OF ABANDONED CONCRETE AMPCHNDO AT ETRIP TING LI ok TR Pai weeny Ferny DRAWING " INSITU UNDISTURBED rea renee 5 6 ¢ eae 75 LONG STEEL 4 [a : 10 (AYG) ASSUMED MATERIAL : GLACIAL TILL (CLAYEY SAND/SANDY CLAY ANCHOR BOTTOM FROM Soll. MASS AT ANCHOR #LE #44 (7YPE'TA -20C) MIXED WITH COBBLES ¢BOULDER, DENSE, HARD FCEMENTED) SHEARED SURFACE, TYP/CAL ABOUT 1h"49 24" SEPARATION OF ay Se oo, ey yay pe Pee ey meme oo a my = = _ < me "NO CREEP MOVETTENT A @ ; AT 0,520 MINUTES Ch oh al y Piltl- 07 TES’ ON 18-INCH DIAK = CONCRETE: ANCE w INSTALLED £ TES : BY 1ECO ON YF g sL E ky CONCRETE ANCHOR TEST PAT i SL kee A206) > WMBOLIANCHOR| = L/L TIMATE > ‘| wo |LoADis)| Maverrenr7,( L 2 2:44 ql ze a si 3.94 RV : C2 4.25 at SS 6 5 70 7S 20 25 to ANCHO LOAD, KIPS : FIG. B-G! CONCRETE ANCHOR PULLOUT TEST DATA ‘30° 35 40 : (TYPE TAe20C) PRAT pg Foueeng owen Cr oc =—_ Sy nay my Ty me ae Pe CHAPTER 4 LABORATORY INVESTIGATION 4.1 GENERAL A laboratory test program was conducted to determine the index, density and shear strength properties of the soil samples collected during the field investigation at the location of the abandoned anchors #1 and #4 near Structure No. 67-6. As mentioned previously, attempts to collect undisturbed samples of the glacial till material during the field investigation were unsuccessful, the in-situ material being hard, dense, cemented, and mixed with cobbles and boulders. Therefore, laboratory tests were performed only on recompacted and undisturbed “samples of the backfill material which is, as placed, a very loose, heterogenous mixture of naturally occurring soils. The laboratory testing was performed by Alaska Testlab in Anchorage, Alaska. The laboratory report containing the soil test results is presented in Appendix A. The suggested laboratory test program is included in Table 4-1 of the text. 4.2 LABORATORY TEST PROGRAM AND RESULTS The testing program included soil density, and moisture content determination, grain size analysis and Atterberg limit tests on seven relatively undistrubed samples of the back fill material. The results of these tests are summarized in Table 4-2. Gradation curves are presented in Appendix A. [oleate] In addition, the maximum dry density and optimum moisture content of a combined bulk sample from test pits at anchor locations 1 and 4 were determined using AASHO T-180, Method D. The compaction curve is presented in Appendix A. The maximum dry density of th soil was found to be 141 pcf at an optimum moisture content of 7.0%. Eleven unconsolidated undrained (U-U) triaxial tests were performed on modelled and recompacted samples. The samples were constructed by eliminating the +3/4 particles and sieving the remaining soil to obtain a material with a grain size distribution parallel to natural grain sieve curve. The samples were then recompacted to densities ranging between 105 pcf to 136 pcf and sheared under undrained conditions. The resulting stress-strain curves and Mohr envelopes are presented in Appendix A. The Mohr circles have been grouped by density into two categories: 1) Loose fill with densities 105 - 112 pcf (approximate relative compaction 74 - 79%), and 2) Dense fill with densities 115 - 136 pcf (approximate relative compaction 82 - 96%). The loose fill behaves like a frictionless soil with a cohesion value approximately 320 psf. The dense fill has an angle of friction of 38° and cohesion of 430 psf. In Figure 4-1 undrained strength (Su) of remolded glacial till is plotted against its modulus of elasticity (E) along with published data a from other sources. = oH 4.3 DISCUSSION AND CONCLUSION Based on the results of the triaxial testing it appears that the strength of the backfill material is significantly affected by the density to which it is compacted. The loose fill (density range 105 - 109 pcf) behaves like a soft cohesive soil under undrained conditions while the denser, well: compacted fill (density range 115 - 136 pcf) behaves more like a dense glacial till under undrained conditions. Comparing the very low in-situ densities determined from the undisturbed samples (density range 68 - 109 pcf) with the density range for the loose soil, it can be concluded that the in-situ fill material in the location of soil anchors 1 and 4 has relatively low shear strength represented by a cohesion value of the order of 330 psf, and friction angle 9=0. Since the undrained shear strength of remolded glacial till at Structure 67-6 is about 2000 psf (Figure 4-1), it is concluded with a reasonable degree of confidence that the undrained shear strength of cemented glacial till in in-situ condition will be significantly higher than that. Co a coopers pum CRA poo TABLE 4-1 SUGGESTED LABORATORY SOIL TEST PROGRAM For soil samples from each trench, the following tests are recommended: 1. 2. Natural moisture and density. Grain size analysis. Atterberg limits. Modified Proctor’s compaction. Unconsolidated undrained triaxial shear test on: a. Samples compacted at 95% relative compaction with optimum moisture content. b. Samples compacted at natural moisture and density. For both the cases a. and b. saturate the samples, and shear at confining pressures, 3c! = 2, 4 and 6 psi. Develop Mohr's envelope and provide the values of c and § for both the cases. ARE FO TR ©5)5 Co GG 1. 2. 3. 5. 6. 7. 8, 10, . 12. 13. 14, 15, vA. Description of Material: Unified Sofl Classification: Frost Classification: In-place Dry Density (PCF): In-place Moisture Content (%) Laboratory Compaction Data (AASHO:T-180) a) Maximum Dry Density (PCF) b) Optimum Moisture Content (%) Relative Density Test Data a) Minimum Density (PCF) b) Maximum Density (PCF) Relative Compaction of Backfill (%) Gravel (%): Sand (%): Fines (%): Gradation: Mean Grain Size, 050 (mm): Uniformity Coefficient, Cu Coefficient of Curvature, Cu Atterberg Limits LL (%) PI (%) Unconsolidated Undrained Triaxial Shear: Test Data Cohesion, ¢ (PSF) Friction Angle, @ (°) Failure Strain, E¢ (% Dry Density, Y'4 fon} - c Madutue af Flaetiadtu! F inet) Waateon ———— Pring ot on woe - . ) eemned etemeeeneemmenene ceeese ——- TABLE 4-2 , INVESTIGATION OF ANCHOR FAILURE SUMMARY OF SOIL PROPERTIES AT STRUCTURE 67-6 A. Backfill Hetenoge neous mixture of naturally occurring materials. GM-SM FI ~ F3 68 - 109 (89) 7.3 - 26.7 (17.2) 41 7.0 105 - 109 48 - 77 (63) 17 = 46 (34) 29 ~ 55 (42) 20 ~ 28 (24) 0.55 - 3.5 (2.16) >>100 2,5 = 5.9 (4.2) 18.3 = 34.9 (24) 0 (NP) Well -Compacted Loose Material Material 330 430 0 40 >4 ~ 5,8 (>4.5) 0.9.7 3.1 (2,2) 105 ~ 109 125 ~ 136 (129.3) 480 = 798 R70 ~ YANN B. In-situ Material (Properties Estimated) Comments and Observations ' 0' = 0.5: Roots and partially decomposed vegetation. 0.5) - 1.5': Tan sandy, gravelly silt. 1.5 +: Gray sandy, gravelly silt (Glacial till) well cemented. GM-SM 140 4A: The backfill around tne ancnor nas veen suojected to 5.0 some amount of disturvunce; however, tnat will not affect the conclusion that tiie back- fill as placed is very louse: - a) thin Shelby tube sample could be pusned by nand in ai some locations; D) also, tne loose sample dropped out of the tuve in some lucations. S| 48: Could not drive Sneloy Tuve in coarse, dense, nard cs and cement glacia) till in- situ. 7: This is the minimum 34 density of processed sui! used 42 for triaxial snear tests, to 24 represent the strengti of backfill as placed around the 2.16 anchors. 15; Soil fraction passing T4-inch sieve was used for triaxial shear tests. © Loose backfill oenaved like Y=U soil and exnivited progressive failure witn large strain. © Vompacted vackfill pehaved like ¢ = J soil. tx- hibited prittle failure ac low strain level, o From educated judgement, we believe that tne ylacial till inesitu is signifie cantly stronger than tne wall eomnacted backfill. Su © 1000 = 2000 PSF (lower bound) * : vr yereue ——w weer —— —= semen peo wceg escuee og Ree py pee eH ern Frey pay eng £ ( Tons /Sq.Ft.) 20,000 10,000 5,000 1,000) 500 100;-— 50 rtiril Calculated from settlement odservations Bosed on Q tests “Approximate ronge for softened ond unsofiened sholes ond mudstones Morgenstern & Eigendrod (28) NOTE: Loborotory tests only on core somples TESTS PECFsSMED oy REMOLDED GLACIAL TILL SAM FROM LOCATION O STRUCTURES 6F- ACCORDING ASTM: “oR AASHO TH" 1 eel el feet neal 50 100 5 to Sy (Toms / Sq. Fi.) - Ficurr 4-VApparent variation of in sita undrained Modulus of Elasticity (E) for placiat tills, with undrained compressive strength (qe). ¢ After Mi Wg ar, I9Fe — Rel Z é i Figqvee 4-l ypowee womsacrn ray ny, waar, preg Peay BARI paR RR Ql A PS ONY AY CHAPTER 5 DESIGN AND ANALYSIS 5.1 GENERAL A study was performed to theoretically compute the capacities of the soil and rock anchors as designed and installed. The particulars of the design of the anchors are included in Table 5-1. The maximum holding power of the 18" diameter, TA-20C, and 12” diameter, TA-10C, soil anchors in "ordinary" soil has been specified by Miner and Miner (M&M) to be 20,000 pounds and 10,000 pounds respectively. The maximum working load for the TA-2H rock anchor has been specified to be 35,000 pounds. To determine the adequacy of the design it was necessary to evaluate the capacity of the anchor under the assumed “ordinary” soil condi- tions. Therefore, it was necessary to define the term “ordinary” and assign soil parameters to this type of soil. In addition, from the results of the field and laboratory investigation it was necessary to determine whether the "ordinary" soil conditions, which were assumed in the design, actually exist in the field. Since there was a discrepancy between the design soil parameters and the field condition, the theoretical capacity of the soil anchors was computed using the shear strength parameters from the laboratory testing for the loose backfill and the compacted backfill and estimated parameters for the dense in-situ glacial till. A oe —— yeorsesery were pew eres eeeny = RR YA BHR ey eg UR 5.2 METHOD OF DESIGN AND ANALYSIS A. Soil Anchors The state of the art in the design of anchors in soil is based largely on empirical data. Design capacities for various, sizes and types of commercial soil anchors are readily available in the manufacturer's literature and design manuals. However, in general, these capacities are based on a set of “average” soil properties. If the actual soil conditions at project site are different than those for which the anchor is designed, the actual capacity of the anchor may be significantly different. Several theoretical methods of determining the actual anchor capacity have been developed; however, the ultimate capacity values computed by the various methods differ greatly, as seen below. Therefore, in the light of the absence of a standard, theoretical design approach, it is a safe, well accepted practice to perform full scale pullout tests during construction to verify the computed design capacities and developing the method of installation of anchors. Three methods of analysis were used to determine the theoretical ultimate capacity of the soil anchors. These methods are briefly described as follows: o Friction Cylinder Method (References 1 and 2) - This method assumes that failure occurs along the surface of an inclined cylinder of soil above the anchor. The cylinder has the same cross-section as the anchor. The ultimate pullout capacity is computed by considering the weight of the soil anchor and the frictional resistance along the surface of the failure cylinder. The frictional resistance is assumed equal to the average shear strength value of the soil along the failure surface. Necro per neon == prea swes wooed Pe pee Neg preg gag tong pray pres, o Meyerhof Method (Reference 3) - This method assumes the failure of the soil mass above the inclined anchor to occur in a roughly truncated pyramidal shape. The ultimate pullout capacity is computed by determining values of several uplift _ coefficients. The uplift coefficients, developed from both theory and smal] scale test results, increase with the friction angle and cohesion of the soil and the depth of embedment. o Soil Cone Method, U.S.B.R. (Reference 4) - This method assumes that the failure surface is the shape of a truncated cone extending above the soil anchor with an apex angle of 60°. The base of the cone has the same cross-section as the horizontal projection of the anchor. The vertical pullout capacity is computed by determining the weight of the soil within the truncated cone. The ultimate pullout capacity of the soil anchors is also limited by the ultimate tensile strength of the anchor bar rod which is 36,000 pounds and 23,000 pounds for the one-inch and 3/4-inch diameter rods, respectively. B. Rock Anchors Grouted rock anchors can fail in one or more of several failure modes. Failure can occur by shearing within the rock mass, failure of the rock/grout bond, failure of the grout/bar bond, or failure of the steel anchor bar in tension. Therefore, to evaluate the adequacy of the rock anchor design, the anchor capacity based on each of these failure modes was computed separately and the lowest value was assumed to be the ultimate pullout resistance. 1. Failure through Rock Mass - Assuming failure to occur to the rock mass, the uplift capacity of the rock anchors was computed by two methods. First, the design-load uplift on the footing was assumed 5-3 er pevneeg yess owe aay Foner, Py r tnd ‘4 ee eS ee to be resisted by the shear stress on the lateral surface area of an inverted truncated pyramid of rock with depth equal to the vertical depth of the anchor bars and with an apex angle equal to 60°. In the absence of shear strength data, based on U.S. Bureau of Reclamation Design Standards No. 10, the shear strength along the failure surface was conservatively assumed to equal 500 psf. In addition, the uplift capacity was computed using formulae cited by Littlejohn (Reference 5) for sound homogeneous rock. In this method, the failure surface is assumed to be conical with an apex angle of 90°. A maximum shear stress of 500 psf was assumed to act over the cone surface. 2. Failure at the Rock/Grout Interface - The ultimate anchor load based on the maximum bond stress between the cement grout and rock was computed by determining the surface area along the grout rock interface and multiplying by the maximum average bond stress along this surface. In the absence of shear strength data or field pullout tests, the probable range of the ultimate bond stress was estimated from a thorough investigation of published data. It was found that typical bond stress values vary greatly due to rock quality and type. The average value of bond stress ranges from approximately 2,500 to 10,000 psf for soft to medium rock. In the absence of site specific information on the rock type, quality and strength it appears that a conservative maximum bond stress of 3,000 psf is appropriate. _ Therefore, the ultimate capacity of the rock anchors was computed using this value. In addition, for comparison, the capacity was also computed assuming a bond stress of 21,600 psf, an appropriate value for fresh, medium hard rock without joints and fissures (Table 5-2). 3. Failure at the Rod/Grout Interface - The ultimate capacity of the rock anchor was computed by determinng the surface area along the rod/grout interface and multiplying by the maximum average bond stress which will develop along this surface. The maximum bond stress was pea orm awe yee — — ware prag assumed to equal 120 psi (17,280 psf) which corresponds to an average concrete compressive strength of approximately 2,700 psi (Littlejohn, 1975). 4. Anchor Bar Failure - Failure of the anchor can also occur by overstressing of the anchor bar. The ultimate strength of the one-inch diameter anchor rod is 36,000 pounds (Reference 6). 5.3 SELECTION OF PARAMETERS FOR ANALYSIS The design soil parameters for "ordinary" soil used by M&M were not made available for this analysis. However, it was Tearned that standard anchoring practices of the Rural Electrification Administration regard an average or ordinary soil to correspond to soil classification 5-6 in Chances' catalog (Reference 6). ~. Chances’ soil classifications 5-6 are defined as follows (see also Table 5-3): Soil classification No. 5: "Medium dense, coarse sand and Sandy Gravel, Stiff to Very Stiff silts and clay; Residual soil, Saprolite, SPT value N=14-25, y=120 pcf, 9=36°, and C=1400 psf." Soil classification No. 6: "Loose to Medium Dense, Fine to Coarse Sand, Firm to Stiff clays or silt or Dense hydraulic fill, compacted fill and Residual Soil. y=120 pcf, 633°, and C=750psf." The average soil parameters corresponding to these soil classifications were chosen for the analysis. ome yee wremoee pare, pire ere ween Beery In the absence of site specific soil investigations for each foundation along the transmission line, a survey of experienced design engineers was made to develop soil parameters corresponding to the average soil likely to be encountered along the line. The results of the survey are presented in Table 5-4. The average values and the values corresponding to + one standard deviation were used in the analyses. Finally, soil parameters were developed from the laboratory testing of the backfill materials collected during the field investigation at structure No. 67-6. The soil parameters choosen for the analyses are included in Table 4-2 and 5-1. Analyses were performed for the soil anchors bearing against uncompacted, loose backfill (as constructed), bearing against compacted backfill, and bearing against the undisturbed dense in-situ material (as designed). The soil parameters for the undisturbed, in-situ material were developed from the published literature for similar type materials. 5.4 RESULTS OF ANALYSIS AND DISCUSSION A. Soil Anchors The results of the capacity computations for the soil anchors are presented in summary form in Table 5-1. The analyses were performed for the 18-inch and 12-inch anchors inclined 45° to the horizontal, as specified in the design. The anchors were installed with steeper pull angles with the horizontal, approximately 56°, which would reduce the capacity of the anchors by approximately 15%. The three different methods of analysis provide a wide range of anchor pullout capacities for any one set of soil parameters. The Meyerhof Method and the Friction Cylinder Method account for the anchor pull inclination and the shear strength variation of the soil- The U.S.B.R. Soil Cone Method is based only on the vertical pullout capacity and the oe —— pure = 2 ea Te PE pa wes density of the resisting soil. The wide variation in estimated anchor capacity is also illustrated in Table 5-5, where several experienced engineers were asked to estimate anchor capacities even with site specific soil information at four separate sites. (Ref. 8) In addition, the calculated anchor capacities vary greatly due to variations in the assumed soil parameters. The two methods of analysis which account for the variation in shear strength of the resisting soils, the Meyerhof and Friction Cylinder Methods, indicate that the anchor capacity in the uncompacted backfill at Structure No. 67-6 would be substantially lower than that of the anchor bearing against compacted backfill or undisturbed in-situ material. Also, due to the lack of site-specific information on the soil conditions at the structure locations the expected variation in soil conditions along the transmission line was accounted for by calculating the anchor capacities using the average Alaskan soil properties ~ resulting from the survey of design engineers and plus/minus one standard deviation in the soil properties. The results based on the average soil plus one standard deviation approximately correspond to the results based on the average REA soil (Chances' 5-6) and the results based on the compacted or undisturbed materials at Structure No. 67-6. The anchor capacities based on the average soil minus one standard deviation approximately correspond to the results based on the loose, uncompacted backfill at Structure No. 67-6. B. Rock Anchors The results of the calculations for the rock anchors are presented on Table 5-1. Analyses were performed for rock anchors embedded three feet into sound rock, inclined at 45°. From the results, it appears that the grout to rock bond governs the design of the anchors. In the absence of site specific data, assuming a conservative yet reasonable value for the maximum grout to rock bond of 3,000 psf, the ultimate erm rey Ree, Pateninag Pweg ed warns woe od tees wot SR pone capacity of the rock anchors as designed, is calculated to be approximately 5,000 pounds. The actual maximum bond stress may be higher, therefore, the capacity was also evaluated assuming 21,600 psf maximum stress. The capacity was calculated to be approximately 34,000 pounds (Ref. 5-2), stil] lower than the 35,000 pounds maximum working load indicated in the specifications. Two alternative designs were estimated, one increasing the embedment depth only, and the other increasing both the embeddment depth and drill hole diameter. Both designs have a maximum pullout capacity of 35,000 pounds. The details of the designs are presented in Table 5-1. The theoretical capacity of the rock anchors as designed appears to be significantly lower than the design value of 35,000 pounds, indicated in the specifications. However, the capacity of the rock anchor was evaluated using conservative values of rock strength and rock to grout bond strength due to the lack of site specific information about rock _ type, quality and strength. In the absence of this information it appears highly desirable to perform field pullout tests to confirm the design capacity. 5.5 CONCLUSIONS On the basis of the literature review and the results of the analyses, it can be concluded that there exists no one commonly accepted or rational analytical technique to evaluate the capacity of soil anchors. The most reliable design method is previous experience in identical or similar situations, which requires site specific field and laboratory investigations to determine the soil conditions at each anchor location. Where site specific information is lacking, analytical techniques can be used to suggest practical anchor types and approximate design loads. However, a specific design requires field testing to assure it will satisfy the design requirements. wrcownay seouT eoweas Rae erry wang barcee aay vanes os MS ay Faq Ree The TA-10C and TA-20C soil anchors were specified for "ordinary" soil "... thoroughly tamped the full depth ...." As seen from the field investi- gation and results of the laboratory testing, the soil density and strength vary greatly depending on the degree of disturbance and recompaction. Based on the results of the capacity analysis, it appears that the anchor capacity is significantly influenced by the strength and density of the resisting soil and thus strongly influenced by the degree of disturbance and recompaction of these soils. It also appears from the analysis that the design capacities indicated in the specifications, 20,000 pounds for the 18-inch anchor and 10,000 pounds for the 12-inch anchor, are high but perhaps reasonable values if the resisting soil is the undisturbed glacial till, and is "thoroughly tamped the full depth -" as indicated in the specifications. However, due to the probable spatial variation in the properties of the till along the transmission line, field pullout tests at typical locations are highly recommended to confirm these values. The theoretical capacity of the "as built" soil anchors, in which the resisting soil is loose, uncompacted or slightly compacted backfill, is significantly lower than the capacities indicated in the specifications. Compacting the backfill to 95% relative compaction appears, from results of the analysis, to substantially improve the anchor capacities. However, field tests are recommended to confirm these results. rey Low wareany ee FRR REE pay FrSERY wera eR een a ey ee ee 5.6 REFERENCE LIST 1. Baker, W.H. and Konder, R.L., "Pullout Load Capacity of a Circular Earth Anchor Buried in Sand", Highway Research Record No. 108 (1965). Woodward-Lungren & Assoc., "Results of Pile and Anchor Installation and Load Tests, and Recommended Design Procedures” (1971). Meyerhof, G.G., "Uplift Resistance of Inclined Anchors and Piles", Proc. 8th Int. Conf. of SMFE. Vol. 2.1, pp- 167-172. (1973). U.S.B.R., "Tranmission Structures", Design Standards No. 10, (March 1965). Littlejohn, G.S. & Bruce, D-A., "Rock Anchors - -Design and Quality Control" Design Methods in Rock Mechanics, 16th Symposium on Rock Mechanics ASCE. A.B. Chance Company, "Electrical Transmission and Distribution Products, Catalog 1-78" (1977). Nixon, I.K. (1974), "Discussion on Papers 22-25", Proc. of the Conference organized by The Institution of Civil Engineers and held in London, 18-20 September, 1974. American Society of Civil Engineers. ASCE Geotechnical Division Specialty Conference, Austin, Texas, 1974, Session 5 discussion. 5 - 10 Lod rs hag Ez Leb bo ES aca ae (WS) INTERNATIONAL ENGINEERING COMER INC. pneet__ye- piper = te ca Project ZEWEW OF CRITER/A FOR izaky T/L _(CvER) Contract N ie Sumagy RESULTS o own Feature REWEW FANALYSIS OF GUYED ANCHOR _ Designed C&® CEBINGS Date S£P7 3, Y3/ con nA evrs ¥ Ps Priblebanl tet aa BUYED ANCHORS Iweetl PING tem__ CAPACITY Checked N68, _ Date (TA-10C. Lge) 7Ja-20c °° (Solly ‘ TA-2H (CRoee). 1. Anchor Designat'm: Gx fossibe Zing “As Lompukd ALTERNATIVE DESIGN|E other Relatcot Data . vements - De signed << o . on 2 Anchor Type Soll 3. Anchor Capacsty. (os) 10,000 #. design € Spec. “1 MEM 5, Anchor Rod Details, = 8) Rod diam( meh). o-75 \) Embedded Rod Lengts (Ft)| 8:0 <) Total Rod Length, (Fi). 9:0 4 Pin® “imate Sheng th (46s). | 2,000 A : Sante Sienaie: sree? hs : “x |( Recucees Strength| atove by | 10 to /57| prvrde prea . rote ahve iio fe SY, or P ye f) Anchor Inelinat™ sth 45° 2 45° 45° 45° Yeopect +o Hor emfat £. Deriled hole ov Crarete Butt Diame ter Comches) ‘ /2. ? Grout Detole tor Reex Bolt: ASSMP TIONS @) Mix Ratio. “res Pieeyl fiszoy 6) Cémertt Type. Comment Comet |lComent Fmd onal dn 9 Admixtures Added - NOT | APPLIICABUE le a= d Placement Temp eva ture(F) g Rack: Cha reeterisfes. a = 4) YP 4 F clanifréa ton | | T {SOFT & | C)No rock foot & f R&D. ; Not 1 te @Ab tert anchor | 4 Neathered/ Ter nted /Fresh. Not | APPLICABLE | knewn M 2 pullcat test olata 3 T Py E FRE ws Olrep mevement 4) Soff Chorackrishes. \ ear Lee i <2" Descriphion $ USC, ~- ~~ -| ORvinmny| GM-sM cm- sm“ Gers a eee? 64-54 OlGN-5M Gay -sm B ' ie Chance'sS Sai clan fication os sole be _ i ! Binceks Tal : Fines Content (7).- - > -- — 1209-25; 20-25) 20o— as | == 20-%| 20- as Zoe= as i Dry Density, ¥4 CREF) = = a - |. 89 130 140 | _ /30 /40 Masture Centent, ) ~ — 17-2 aoe 5-0 io Fl 5-0 NoT — Shear Strength, Su (PSF) - -- -| ~— - aoeie my 320 Hee ex a Cokesim , C, "DSF - - — 320 wae i ro aac #30 ze 1500 Frictim’ Angee, J Degen - - a i | - = [Fert acphininy” = =| = | moh | petal subse’ | = | raph | gett organ [DO Depth « 4 Cor me frost — |varnaclé 24 FoR THER INVEST GATION | Uy) Fhreeness GB Amie harper - — May Nol BE cerita & IF FICUNDATIGN MATERIAL ae 3 > GLACIAg TIL QW WU CINWNA LUA COUN DoO AWS VU mite, ae, Project KEWEW OF CRITERIA FOR 38K V T/L CCVEA) Contract No.__ File No. _______ </e Feature REVIEW £ ANALYSIS OF GUYED ANCHOR _ Designed C£B/NGB pate __7/3/8) os Item__ CAPACITY : Checked Date _ = a TA - 20C TA- 20 4 : melbeger ee srrers | LAS fucincem ee sre | AS | As Gppputed [nermmant™ DETEVR ST a- REET sient Designes [Burtt eaten Dessnes) Guilt oa, ; AUTH] | Aur-2 | a, Ol} Lr ieee — a St ey + 4) Displacement (wnch) =2- <7 Aor ) very ge) "2 9” i </'" [MOF Sped = pom : Lower ff 220 eee Mest sati- Speuph ene! Metre, Schteemitie — | Cn ih Seansel —+*+—_. . { D tha t 5 im ; Oren : | } 12) Comments ¢ Recommendations ad ~fecfery Maw, Dew] +s0 “fp — | farndtat dear | ; 5 ee : a the . bere (ore | Fema: | ‘ undieate a Capac ty at % j —— a P peterein te “* ar bse onstatta 74 J™ lctegeetve - ayn fi Ont, too high | un Gtom~ PUP OIE | Her ohatlow vee | anchors | Sheut d be 5 pow by under - | erotaltec! lanchor~ jAcgher cape fe analtns| ® Sonitelesad ‘ G@mehors| - P *“tuthing MAT: untest mstealeah (23,000 Bs)" ote, = erent yoo ry pio wt it pulls Soll youd aud prov 1 PIECO Bene: | vin tntenped veste 7 - against Ka 10 WIE pore. men - benstattect | cemies Mithout tpt encher | a “davbad ut tert — ship at | anchor tet yeas [Petemt tats, j Crd staried Vencher Pl stnichate Netratuve tpg Road alte ee | cath “4 cut tests, Ce-6 ; ey Comrments ‘ # I vod fronth w I Deoviyn a ene jp rantter: tile _ . i ither tp | : Fer ether | j Amp reviem eb i mat a trench-| perry, Lom ments aud achiatath . ge ~Ung tool an | Sh a @eo | CE) ! Considered | Thea apo wih & Small Col @ | | jas short | pacer gett tare Eamon bate | _ | Beth, anchor Findl tapi | tender Colanw 1 audreckt fer of © | |tremeh and; a / | whee: \ Shred ‘ 1082 Cof(@), | bacctlled | ee | lap ee yet d. i | Pelarve, } Smpachio, | | i Casts - Dr i | NITES: () Sow eOndITIONs AT structure 67-6 IC gon peoPERTES ESTIMATED FoR uNDdISTUuRED (a GLACIAL THL RT STRUCTURE 67-GC. at (t\ AREAL THEOEENCAL CACRCITY 2(@) AVERAGE THEORETICAL CAPACITY WITH ESTMATED Soil PROPERTIES, @) cprPrcitX Feom PoU-outT TESTS ON ABANDONED AncHorS AT STRUcTURE CF-C (SEE APPENDIX — AB) @ BASED on pull-oUT TESTS PERFORMED ON TECO ANCHOR ACCERDING TO MEM DRAWING 7-6 (SEE APPENDIX -A FB). INSTALLED AT STRUCTURE @) ACHIEVABLE /N UNDISTURBED GLACIAL TL 4S Ewe AT STRUCTURE £7-6 WITH “Prop DRAWING AND BACK UP -Sor TEST COUNTER cd SPECIFICATION Awd DATR - j © fev iff oud broker, voc on untested wee aud also wrth at teof-amnchor Pobeut tat data , @ Fresh, medium hart to hard rece withent ponte Qud issures ancl aerign Capacity urvifed | by - trrat “ancher pel? cup-tent program - Bkematve Leac'gns fr geeky or umtertecl roanaud or wifkret ancker pull-sut tre, . ta Oe i a— berry ey Ey pe ss one TSR = ART TABLE 5-2 Guide to Bond Stresses For Three Catagories of Rock [Koch, J.L. (BBR, Australia]. Private communication to Nixon, I.K. (Ref. 7) Bond Stress* 2 Rock Type 1b/sq in N/mm Weak rock 50 - 100 0.35 - 0.70 Medium rock 100 - 150 0.70 - 1.05 Strong rock 150 - 200 1.05 - 1.40 o Note also the allowable bond of 304 psi (2.1 N/mm?) between tendon and grout stipulated in Australian Anchor Code. o The corresponding bond between deformed bars and 4350 psi (30 N/mm ) concrete recommended in British Code (CP 110) is 320 psi (2.2 N/mm 2). * Care must be taken before applying these values, since degree of weathering (seldom quantified) affects not only the value of bond stress at failure but also the load-deflexion relationship during service. 5-11 Chance's Soil Classification System and Its Inter-relationship With TABLE 5-3 sas F "Average Soil" in REA manual - Probe | Typical MENTS* Values Blo! Count CoM TS in.-Ibs. “N™ per Class Engineering Description Familiar Names’. (Xm) [AS iiss 0 | Sound hari rock, Granite... Basalt. NA NA. unweuthered Massive Limestone ROD = 37 1 | Very dense amlor ‘ache? weathered | cementerl sane sandstone 750-160) 60-100+ f gravel and ovhblest? (30-205) 2 | Den-e fine Very jBazal till, boulder day: * luche: weathered 45-60 laminated rock 3 Glacial tilh: weathered shales, schist. gneiss | 500-600 35-50 jand s; 65-74 ‘4 lcial til: hardpan: | 490-500 23-40 imaris (52-65) : 2 il 2 5 | Medium dense coarse sand Saproiites, residual soils] 300-490 | 14-25 Designated as "Average Soil” in REA and sand s ek ait to (39-52) Very stit? sits and lays oe © | Loose to medium dense find Dense hydraulic fk, | 200-300 7 Transmission Line Manual. The to coarse sand. firm to compacted fill: residual | (26-39) : Sus cass ail silts a parameters adopted for anchor design —s [Fivod plains soils: Jake | 100-200 +3 Jelays: adobe. gumbo: fill! (13-26 . are as below: ~~ ess than 05 . wo (0-32) stenly and the ASTM blow count may be of y = 120 pcf.; c = 750-1400 (1075) psf. 6 = 33-36 (34.5°) \¥ Mean differnt soils in different areas. sep enough, by the use of extens ns, to penetrate a Class 5 or 6. <7 or 8 Soil. anlerlying the * Based on personal communication with the U.S. Department of Agriculture, Rural Electrification Administration, Design Branch. * For REA anchors rated at 8000 lbs capacity, the failure load capacity of 25000 Ibs was established from anchor pull-out tests. A factor of safety of 3 is adopted for Transmission Lines and 1.5 for distribution lines. 5-12 wren Rortesven on Wek Kat twas ver, sae para wea PAGE pro Teeneg Bey SET Pe OP OY TABLE 5-4 DENSITY AND SHEAR STRENGTH PARAMETRS FOR AVERAGE ALASKA SOIL - RESULTS OF SURVEY Density - (pcf) Vary ¥Total Cohesion, C (psf) Friction Angle, o° Range 90-120 105-135 Mean Value 103.5 h2bs5 Mean + 1 Std Dev 113.0 131.0 Mean - 1 Std Dev 94.0 112.0 5 - 13 Shear Strength Parameters 0-120 415.0 812.0 18.0 20-40 29.3 36.0 22.5 ea oe eee! eo pre wragy pete werscr on wee wreng pereeng beenue Feeney {mR were, TABLE 5-5 An example showing variation in anchor capacities (KIPS) estimated by experienced engineers for four separate sites. (Ref 8) Name of Calumet Washington Morristown Park Engineers Basis Harbor Metro (N.J.) Central Dr. Costa-Nunes, Theory 160-510 125-300 80-260 70-380 Teenosolo Mr. Malijian, Theory 300-500 250 200-250 400-600 Le-Roy Crandell] Mr. Nelson, Experience 250-300 120-150 100-1 20 250-300 Spencer, White & Prentis Dr. Murphy Theory 295 150 120 215 Dr. Bassett, Theory 200-290 130 125 145-205 King's College Actual Test Load Data 320-450 160-220 150-260 200-280 Remarks: 1}. Please notice the wide variation in estimated anchor capacity even when the engineers are provided with basic constructional and soil investigation data. - 2. Dr. Bassett of Imperial College, London suggests that such estimated capacities should be at the low end of actual anchor capacity. 5 - 14 een a —w" a cote een wierog ne, ed pena FRRABS au ns oe Os | peur 6.1 CHAPTER 6 CONCLUSIONS & RECOMMENDATIONS CONCLUSIONS Soil Conditions In-situ soil at the location of Structure No. 67-6 jis dense, hard, well-cemented and over consolidated Glacial Till (GH-SM). From the consideration of density, impermeability, strength and frost resistance, it is an excellent material in in-situ condition. No ground water was encountered in the trencnes nor any ice particles were visible in the soil formation. The material exhibited favorable characteristics typical of basal tills. : Therefore, the glacial till at Structure No. 67-6 is classified as above "average soil" (Chances' Soil Classification 3 against 5 to 6 rated as average soil). It is therefore concluded that the anchor failures at Structure No. 67-6 can in no way be attributed to poor soil conditions. If in any other locations soil conditions were found to be comparatively poorer than that at Structure No. 67-6, greater distress of the soil anchors should not be surprising. as ca eran — Sy ee eg Workmanship Norkmanship at Structure 67-6 is judged poor from our examination cf two anchors at that location. The deficiencies found were as follows: 1. The method of anchor installation was poor as the anchor was embedded inside the loose trench backfill and no advantage was taken of the high passive resistance of glacial till by not wedging the anchor against the undisturbed trench wall. 2. The backfill in the trench could be considered almost as an uncompacted fill. 3. The anchors were installed at an angle much steeper (55°-56.5°) than that provided in the drawing (45°). 4. Unacceptable displacement exceeding a foot occured under loads apparently within the specified holding power of anchors. _ 5. If failure load is defined as the maximum load which could be applied on the anchor for an accepted maximum movement (say 2-inches), the residual capacity of the five abandoned anchors at Strucure No. 67-6 subjected to pullout tests were in the range of 12 to 15 kips. C. Anchor Design and Specification 1. A type TA-20C anchor rated at 20,000 pounds capacity, installed ; by IECO according to CVEA specifications at Structure No. 67-6 ' developed 23,000 pounds load for 2-inch movement in recent © pullout tests. The anchor's long term load capacity may be i assumed as 16,000 pounds. i 2. Anchor design procedure is still @mpirical, and therefore, in all major projects, trial-anchor pullout tests should be i performed to verify the design capacities and evolving the method of installation which will result in an achievable end product. In this case, no tests during construction were pana made. Therefore, our computation of anchor capacities should be considered as an estimate of possible range, and our con- Pa clusions are based on educated judgment. wiaw w If anchor types TA-10C and TA-20C are properly installed in Glacial Tills like that encountered at Structure No. 67-6, its { safe long term and short term capacities are estimated to be 16,000 pounds and 23,000 pounds respectively, but need to be backed up by proof testing. 6.2 RECOMMENDATIONS A. A continuing surveillance of anchor installations at heavy angle and dead-end structure locations should be carried out for a few seasons to assure that no movements indicating potential faulure occur. Reference marks should be established reported by Miner and Miner that they have established such F on anchor rods to provide a base for such judgments. (It is 5 references in a number of locations). WATay Ga WTR | Rory neq pay wag PSEA, Scary na 6a It is expected that where anchors have been installed in strict accordance with the specifications in soils of similar class to that tested at 67-6, no significant movements will occur. On future installations, it is considered important that field testing of anchors be performed at sufficient locations to assure confidence in the anticipated performance which would be based on soils information developed during the design process. This shold be done by Contractor personnel under supervision by the Resident Engineer and/or Inspectors to provide all parties with the complete awareness of soil types, installation techniques and resulting performance in advance of the many installations that would follow. A suggested outline for field testing follows: (a) For each anchor determine its short term (including overload factor-extreme transient loading) and long term Toads (steady state). (b) Method of testing will involve step by step incremental loading up to 150% of the long term load. (c) Criteria of Acceptance of Anchors (i) The maximum deformation should not exceed 1.5-inch under the roof load (150% of long term load). 7 (ii) For selected anchors proof load should be maintained for 24 hours and the drop in load should not exceed 5% and the deformation also should not exceed 1.5-2.0 inches. This test provides a better indication of ws the long term creep behavior and safe load capacity of anchors. Daisies warns Pasar mene wenvsa pens ean? waa ween? pang pay Bare form REFERENCES Milligan, V., (1977), "Geotechnical Aspects of Glacial Till”, p. 269-291, GLACIAL TILL, An Inter-Disciplinary Study, The Royal Society of Canada Special Publications, No. 12, Edited by Robert F. Legget. Johnson, G.H., and Ladanyi, B., (1971), "Field Tests of Grouted Rod Anchors in Permafrost", 24th Canadian Geotechnical Conference, Halifax, Nova Scotia, September 1971. White, R.E., (1974), "Anchored Walls Adjacent to Vertical Rock Cuts", Proc. of the Conference organized by The Institution of Civil Engineers and held in London, 18-20 September, 1974, Paper 23, pp. 181-188. Mitchell, J.M. (1974), "Some Experiences with Ground Anchors in London", Proc. of the Conference organized by The Institution of Civil Engineers and held in London, 18-20 September, 1974, Paper 17. — Bement poeanens, prawns rhe Fag Ara. Ram APPENDIX - A CVEA 138 kV TRANSMISSION LINE REPORT ON SOIL INVESTIGATION AT STRUCTURE 67-6. Prepared By: Alaska Testlab, Anchorage, Alaska September, 1981 : y Alaska Testlab. 4040 “B” Street Anchovns, Alaska 99503 Phone (907) 278-1551 {Tslecopies (907) 2 272-574 August 27, 1981 W.O. #A20018 Robert W. Retherford Associates Division of IECO, Inc. 813 "D" Street Anchorage, Alaska 99502 Attention: Mr. Dale Steeby Subject: Report of Observations and Soil Test Results Tower 67-6 Anchors, CVEA Transmission Line, Valdez to Glenal len Dear Mr. Steeby: At your request, Mr. James Finley, Alaska Testlab geotechnical engineer went to the site of Tower 67-6 on August 15, 1981 to assist in an investigation of the cause of the failure of tower anchors. The tower is located just off the Alyeska Pipeline Company right-of-way, approximately fifty miles north of Valdez in the Chugach Mountain Range. The scope of our work was limited to logging of the test pits, obtaining soils for laboratory tests, and conducting those tests. The task of determining the cause of failure and recommending methods of preventing future failures is to be done by others. The general layout of the transmission towers and the failed anchors is shown on-Figure 1. SOIL CONDITIONS Two test pits were dug with a tractor-mounted backhoe. The pits were placed alongside of Anchors 1 and 4&. Similar natural soils were encountered in each test pit. The natural soils are described below. : - Layer 1 - Dark Brown Organics. This layer varied in thickness from & to 6 inches. The material consists of roots and partially decomposed vegetation. Layer 2 - Tan Sandy Gravelly Silt. The top portion of this 1.0 to 2.0 thick layer contains some volcanic ash and organics and is more silty than the material : lying below. The upper portion of the layer also contains colluvium (material transported from uphill by wind and water). However, with depth, the soil is derived from weathering of the underlying glacial till. Figure 2 shows a typical grain-size distribu- wea cco — ay peut Preeeene promsang Robert W. Retherford Associates August 27, 1981 Mr. Dale Steeby Page 2 tion curve for this material. tts moisture content was 22% and its liquid limit is 35. The plasticity index was zero indicating that the material is non- Plastic. Layer 3 - Gray Sandy Silty Gravel. The third soil layer is a glacial till. As illustrated on Figure 2, the soil consists of approximately 22% silt and 40% fine to coarse sand. Cobbles and large boulders are pre- sent. The gravel particles are subangular and the soil is well-cemented and very dense. The test pits extended to a depth of 6 to 7 feet. ANCHOR_ INSTALLATION Figure 1 shows the general layout of the anchors. Sketches of the two anchor installations observed are shown on Figures 3 and 4. Naturally occuring soils were as described above. The anchors appear to have been placed in a trench excavated with a backhoe. Also the tie rod was placed in a wide trench. The excavation was backfilled with a hetrogenous mixture of nat- urally occuring soils. The fill was very loose. At Anchor 1, a 2-inch diameter rod could be pushed into the fill at least 12 inches by hand. In the naturally occurring soils, the rod would not penetrate into the trench wall. As shown on the sketches the cone reacted entirely against loose fill. LABORATORY TEST PROGRAM A laboratory test program conducted to determine the index and shear strength properties of the soil. First, the density and natural moisture content of the soil were determined. During the field program, attempts were made to push brass tubes into the soil. The undisturbed soils were much too dense for this sampling technique to be successful. The presence of large gravel in the fill soil and its looseness, also made attempts to obtain relatively undisturbed samples in the fill diffi- cult. The soil densities, moisture content values, and Atter- berg Limits measured obtained are listed below: Moisture Density Anchor Soil Type C%) CPCF) Atterberg Limits 1 Till Fill 15.0 1 Till 10.7 LL = 18.4 P.1. = 0 1 Fill 26.7 68 (?) 4 FIR... 24.9 89 4 Fill 14.5 109 4 Weathered 21.7 LL = 34.9 P.1. = 0 Gib! desea 4 Till 7.3 LL = 18.3 P.I. = 0 eoercag, coe, prea — a my «OCCU er Robert W. Retherford Associates August 27, 1981 Mr. Dale Steeby . Page 3 A AASHTO T-180, Method D, moisture-density relationship test was preformed on a combined bulk sample from the test pits at Anchor 1 and 4&. The grain size distribution is illustrated on Figure 26 and the T-180 test results are shown on Figure 5. The maximum density of the soil is 140 pounds at an optimum moisture content of approximately 7 percent. Unconsolidated undrained shear strength samples were then constructed by eliminating the +3/4 inch particles since our traixial cell is set-up for 2.5 inch diameter samples. Next the soil was sieved so that its grain-size curve paralleled the natural grain size curve as illustrated on Figure 2. This procedure was suggested by Nani Banerjee of IECO. We were also instructed to compact the soil to approximately the in- situ moisture and density of the natural soil and of the fill. This was not possible because the grain size distribution was no longer the same as the natural soil. The optimum moisture and density are no longer the same. Table A contains a summary of the test specimen properties and a summary of the test results. Figures 6 through 8 show the stress-strain curves. Figure 9 shows the Mohrs circles for the loose soil and Figure 10 shows the circles for more dense soil. The test values are not uniform and appear to be very inconsistent. However, the strength of the soil appears to be greatly influenced by the density as shown on Figure 11. The loose soil (density range 105-109 pcf) appears to behave much like a soil with no friction. The cohesion value appears to be on the order of 330 pounds per square foot. The denser soil with the undrained conditions appears to be- have as a soil with both cohesion and friction. By con- structing Mohrs circles using yield stress values and chosing the tests with higher strength values, an angle of friction of 40° and cohesion of 430 psf were obtained. We have recently completed a testing program with very similar soils from the Valdez area. The grain size curve of the soil closely matches the soil at the transmission tower as shown on Figure 2. Twelve consolidated undrained tests on six inch diameter, eighteen inch high samples were conducted and a cohesion of 450 pounds per square foot and a friction angle of 40° were obtained. The samples were compacted to 130 pounds per cubic foot. What the tests conclusively prove is that the strength of the vt in-situs, dense soil is much greater than the loose fill soils, even if the fill did not contain any organics from the surface layer. erway BOAT aug Wray wang pane wey ey meg wy me | Oy | BRE A Robert W. Retherford Associates Mr. Dale Steeby August 27, 1981 Page 4 We trust this information is sufficient for your present needs. If we can be of further service to you on this matter or on future projects, Sethe weeteonnes James R. Finley, Jr, i BED prrereerer oe Ry RoressWN Maga JRE itt le pe, CEA Se: please contact us. Sincerely yours, ALASKA TESTLAB Jones he Fastey f James R. Finley, Jr., P.E- Approved by: KQ. (L Nchals Melvin R. Nichols, P.E. Partner TABLE A TRIAXIAL TEST RESULTS SUMMARY Strain : Confining Dry Moisture at Yield Pressure Deviator Density Content od max Dewiator Test (psi) (psi) (pcf£) (%) ) Stress 1 2 v4.5 112 Oo7 4 2) 4 V4 115 10.1 4 3 6 4.6 109 10.1 4.2 4 4 353) 109 9.1 5.8 5 2 30.4 130 922 729 17.0 6 4 3133) 129 8.9 sae, 27.0 7 6 11.4 125) 6.8 1.0 10.0 8 6 20.2 127 9.0 2.7 19.0 9 6 11.7 129 8.5 2.0 9.5 10 6 4:2 105 8.6 202. 11 6 32.9 136 9.0 3.4 30 lu-1 NOTE: : ALL DIMENSIONS ARE APPROXIMATE Q © STEEL POLES, HEIGHT =75° d FAILED ANCHOR | @ @ eae ee yl i \-EXISTING ANCHOR 3 UNDER TENSION j | a - wi 6 i DISTANCE FROM EYE OF FAILED ANCHORS TO i GROUND SURFACE j ANCHOR LENGTH (ft) 4 5 6 7 FAILED ANCHORS 1 , = 48.28" 8-2 2 nia i |e] a 17’ - i 3 35 j 4 3.0 5 3.0 © ©0 EXISTING ANCHORS I 6 3.5 “F UNDER TENSION i 7 350 © © (ATTACHED TO ' - DEADMAN) +t i 4 ; i LOCATION OF ANCHORS [ TOWER 67-6 j _ - FIGURE I ——h a reg Sanne omy ema Gay aa PEDAL] ware Fay, pana aoe —* —_ — eae apes SIEVE ANALYSIS HYDROMETER ANALYSIS HUMBER OF MESH PEA INCH, US. STANOARD ww ° 2 ee 2 Sl hee inion oe eM et Se we oo 28 8 & 88 ge 358 85 8 8 3883s 38 g 3, 100, 90 £0 20 ~ ° 3 $s 8 8 PER CENT COARSER BY WEIGHT PER CENT FINER BY WEIGHT & 10 ° 20 oo O oovwnwm nN -e one nm =a ony = ow = 8 88 8hon & 2 ; $088 9 8 e888 3 3 8 ” ‘ @20o00 8 2 GRAIN _SIZE_IN MILLIMETERS a aa ans [ee oar la eet ces | ay dwaioes (crme] | STDRY SANDY GRaveL (GUACIAD IDET ie herd By pan er | @_[ancuor 1 ptt | ee TRIAX, SAMPLI be M | _GRAVELLY SILTY SAND | [ANCHOR 4 [1 (if i-a' GRAIN ‘SIZE DISTRIBUTION FIGURE 2 i) TAN GRAVELLY 1.5] SILT W/0R FILL, VERY LOOSE GRAY GLACIAL TEE VERY DENSE FILL EXTENDED -LATERALLY AT LEAST 2' FROM BAR & . NOTES: 1. FOR DESCRIPTION OF SOIL UNITS, SEE LETTER ' 2. ANCHOR TYPE - TA-20C 3. TEST PIT DEPTH = +6 FEET TEST PIT LOG ANGHOR | FIGURE 3 TAN GRAVELLY SILT W/ORGANICS FILL ,VERY LOOSE FILL EXTENDED LATERALLY AT LEAST 1L5' FROM BAR & GRAY GLACIAL TILL VERY DENSE FACING EAST NOTES: I. FOR DESCRIPTION OF SOIL UNITS, SEE LETTER i 2. ANCHOR TYPE — TA-20C 3. TEST PIT DEPTH = £7 FEET TEST PIT LOG ANGHOR 4 FIGURE 4 wioIsture/Density Helationsnip Of SOs ~ oa | ASKA-TESTLAB ~ A20018 VALDEZ DATE 8/18/81 oo W.O. # CLIENT NVEST. UY PROJECT AASHTO a METHOD: ASTM MATERIAL TYPE__SILTY GRAYELLY SAND COMPACTION STANDARD: DATE RECEIVED __8/17/81 3233 and 3234 SOURCE___ PROJECT STTE LAB NO. —_——_—_—_— DEPTH LOCATION SUBMITTED BY JAMES FINLEY TEST METHOD: OPTIMUM MOISTURE (%)_7-9 xX MECHANICAL MANUAL SAMPLE PREPARATION: MAX. DENSITY (P.C.F.) 41 2.75 SPECIFIC GRAVITY. DRY — MOIST. ATTERBERG LIMITS MOISTURE AS RECEIVED FIGURE 5 MOISTURE, % if - tN Oo 03= 4 PSI Yd =116 PCF DEVIATOR STRESS (PSI) a 3 Yd =112 PCF @) O3=6 PS} Yd =109 PCF i .- O3=4 PSI } . Yd =.109 PCF i j or rr a + + —r 4 . oO 2 4 6 8 10 2 i i STRAIN (%) a Fal nn rar Ra TRIAXIAL TEST RESULTS | STRESS - STRAIN CURVES FIGURE 6 [} 35 © O03 = 2 PSI 03=4Ps © : Yd =130 PCF ¥d =129 PCF i! 25 20 ® O03=6 PSI Yd =127 PCF 15 DEVIATOR STRESS (PS!) 10 @03= 6 Ps! Yd = 125 PCF Tv T Oo 2 4 6 8 10 STRAIN (%) | TRIAXIAL TEST RESULTS STRESS-STRAIN CURVES ees = FIGURE 7 30 @ O03 = 6psi Yd =136 PCF [ 25 - ql ® 20 cS wo i! 3 i il no 15 ce oO il < a = a O3= 6 PSI Yd =129 PDF 10 O03=6PSI Yd =105 PCF tT T tT oO 2 4 6 8 10 i2 i STRAIN (%) Sere eee cc ee ee ITT COT TRIAXIAL TEST RESULTS | STRESS -STRAIN CURVES FIGURE 8 SHEARING STRESS (PSI) 304 25-] nN oO mal “8 a all 10> 1 C = 2.3 PSI= 330 PSF 15 20 * NORMAL STRESS (PSI TRIAXIAL TESTS RESULTS MOHR'S CIRCLES nog — CS gC FICIIRE OQ acing asta anes “204 SHEARING STRESS (PSI) 15~ 10- 136 PCF 129 PQF 130 PCF 10 15 20 25 30 NORMAL STRESS AT YIELD (PSF) TRIAXIAL TESTS RESULTS ‘ MOHR'S CIRCLES FIGURE | As 30 ©5 KEY © conFininG PRESSURE= 2PSi | 25 4 CONFINING PRESSURE = 4PSI © CONFINING PRESSURE = 6PS! <0 GB, o & ; o i o ww : m 15 f @ i fe Oo i = 8 By a = 7 ae 10 : a i re & pray a 10 TT i T | 105 10 US 120 125 130 135 f DRY DENSITY (PCF) TRIAXIAL TEST RESULTS DEVIATOR STRESS VS DRY DENSITY FIGURE II rn a on een in nt tence ence ee ne remnant rane em ew APPENDIX - B eel i i CVEA 138 kV TRANSMISSION LINE REPORT ON SOIL ANCHOR PULL-OUT TESTS | AT STRUCTURE 67-6 { Prepared By: i Van Gullik & Associates Anchorage, Alaska oe ee September, 1981 ee ae wees od way NE OU Oe Ne wy OULU LQULIIN Re er mee be er GUN UD cu Le rere ee Ar > September 95, 1982: Mr. Dale Steeby Associate Engineer International Engineering Co., Inc. Robert W. Retherford Associates Division 813 "D" Street P O Box 6410 Anchorage, Alaska 999502 Re : Our Project E20612 Your P O AL 1463 Enclosed are three copies of our report on the anchor testing CVE structure 67-6. Please forward one copy to CVE to keep them posted. By copy of this letter, I will let Jim Fillingame know what is going on. Also enclosed is a statement of our charges for the testing. If you have any questions, please let me know. I will be in Anchorage this week and will call you. Very truly oe VAN GULIK & ASSOPIATES, INC. Jo ik, PE Enc cc Jim Fillingame JVG/nk — — pre peerre peepee meme premmeng pee pron To : International Engineering Co., Inc. 813 "D" Street P O Box 6410 Anchorage, Alaska 99502 Attn : Dale Steeby, Associated Engineer Nani G. Banerjee, Ph.D, Principal Geotechnical Engineer, San Francisco Office TESTING OF EARTH ANCHORS STRUCTURE 67-6 SOLOMAN GULCH-GLENNALLEN 138 KV TRANSMISSION LINE Re Our Project E20612 Your P. O. AL 1463 By : Joe Van Gulik, PE Berkmans Wick, Civil-Structural Engineer VAN GULIK & ASSOCIATES, INC. September 8, 1981 TT Teter erematemac nner oar nen rman WE en oe RN TOT IE TERI a Ts eneeme cena amnaeiternnmtap ama ' 2.0 ro ors eo, rad TABLE OF CONTENTS INTRODUCTION DESCRIPTION OF TEST AND RESULTS APPENDIX PHOTOGRAPHS _—-* sal — — | VAN GULIK & ASSOCIATES, INU. 1.0 INTRODUCTION Anchors securing structure 67-6 of the Soloman Gulch-Glennallen 138 KV transmission line had failed and were pulled out by the guy wires attaching these anchors to the towers. To investigate these anchors and to determine their holding power, Van Gulik & Associates tested the holding power of the anchors which had failed and also tested one anchor installed according to the specifications during the day of the test. The anchors were tested with a portable test fixture capable of pulling 60 kip. we bani weer Beebe yee aoe — —— —_ a: paar iam t 2.0 DESCRIPTION OF TEST AND RESULTS The test crew of Van Gulik & Associates tested six anchors at structure 67-6 on August 15, 1981. The tests were witnessed by Mr. Dale Steeby and Nani Banerjee, Ph.D, both of International Engineering Company. The testing was performed with a portable hydraulic tester with a maximum loading capacity of 60 Kip. The anchors were concrete slug anchors, approximately 18" Giameter, buried 7' deep. They were identified as TA-20C anchors. (See drawing at the end of this section.) The anchor fixture drawing, scale and calibration material is duplicated in the appendix for reference. A drawing showing the location of the anchors at structure 67-6 as well as a drawing of the anchor itself is shown at the end of this section. Also included is a copy of the line itself and the location of structure 67-6. The depth of the anchor is measured along the anchor rod: and not the vertical depth. The actual test force and anchor movement is measured as follows: "A stainless steel scale is attached to the anchor rod. A string line, supported by stakes spaced 10 to 15 feet apart, is used as a measurement reference point. An initial reading is taken at 1 Kip. The load is then increased in 5 Kip intervals. Each load is held for five minutes, and a measurement reading is taken at each load. The movements are recorded on the field test sheet. This data is used to graph anchor movement as a function of load. The actual field record sheets are copied in the appendix. The anchor movement as a function of the load applied is plotted and is- '! shown in this section. aa wees VAIN GULIIN & Reem wer tt me A total of six anchors were tested; five as originally installed and pulled out by the tower guy wires approximately 3 feet, and one anchor re-installed according to the specifications at the day of the test. All five original anchors failed the test between 12 and 15 Kip. The re-installed anchor held 23 Kip and failed at approximately 30 Kip. As the design load is 20 Kip, we conclude that this anchor passed the load test. The other five did not pass the test. It has been our experience - and that of the industry - that anchor movement in excess of two (2) inches at rated load is considered a failure. The angle of installation with respect to the horizontal was between 50 and 57° and the protrusion of the anchor rod above the soil was 3 to 3% feet. The anchor depth, measured along the anchor rod, is therefore approximately 65 to 7 feet. This is assuming a 10 foot rod with the anchor mounted at the end of the rod. Vertical depth, assuming the above figures, of the anchors was approximately ' 54% feet measured at the nut and washer holding the red to the concrete anchor. (See the drawing of the anchor TA-20C in this section.) As the reinstalled anchor did hold 23 Kip when properly installed, it is possible that the installation method of the five anchors which failed might have been responsible for the test results and failure. Photographs taken during the tests are also shown at the end of this section. “B.WreK BY \ TEST NO, ; G7-G LOCATION ANCHOR TYPE: SLus | TEST DATE: 8- 15-8! 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FERRER SEeECERE ECP SCEEEE Oi BrERECERRE ECE EEC ERSC Ere |: COSee REE ECR REE cet “ame! » BEECERCEEEREREEEEEECECSS Ee sf cofero| eo] foes ashen] xcs) a fins f aed co] es fan | tend ann fess a | cs cel ssn fos os = 1 bi cel ceded ad end (eG 2 (Py Pf Ft, PB See ee eee eee eee ae ISS Siololed alate) aie teletetalelabere tee EISi ete |e| Nels o ErRec eect eee cece ee eee anf ou ff a sin ff fe wn | am fraiche | anf am mf fan ao as > oa Se ee RE Ly FREEEERE EER EEEEECEEer cee z PERE Re ECE eeceeece etc eleic ca 9 aa o EA tt : oS oO - _ ANCHOR DEPTH: COMMENTS te ei went enna tenn eect alt tal tal al ted tl seme tamed tote hemmed B.wWwick BY SLUGS ANCHOR TYPE LOCATION: G@7-/7- G ANCHOR DEPTH ane" 1S- @l TEST NO, :B-15- Rr it a TEST DATE HBS COMMENTS : N SEE EEE _ a EECEE CHEECH: bees fs eb eaad Noo bese asa oe hts ee ett, PEECEEEE EEE FECES EEECEE] eR ERE RE EEE SS e ee REE eRe cece letclelcke FEEEEECEC EERE reer HERE EERE EEE EERE eee ERC EERE KER EE eee EERE RCC ee eee KEEPER EE EEE CEP err rrr errr | EEC EEECEE EEE SCE eee a fae nae fff ae ef ff hn me fmf ffm | feta fre | wf af afc tt i a th poe ae ed oe fae fae] | we] ele | el lee we ee | we | oe] | | oe PEPE P A “EEEEE EEE PERE EE rr SEEEEE EEE FH | ef] st-- Cece PREECE PEI EE PEER EEE ee eeletele|staes acl -jal-l- PEREEE EEE PERE cEEEEE EEE TEEEEL Coa 50 40 30 20 10 LOAD, POUNDS (x1000) 60 PEPEERRECERE EERE EER CeEcece H CI CeCscr errr Pee EEE EEE EE HEE-EE RHEE Q PtP YE Po Da al tt Det BP} an Pe it Ui a et lL ¥ el la Gt sl te EH ° [7] YU PEEEEPEEREREEEE CECH EH eer] 2] ¢ PERE EERE ECE ER rece eee - soafasel as} Doles she e ai a eal tates ead alia ata oad estat oleate etea|m| ete |e|=(alale = ott tt sl pot nt nt ot el Fal tt Ft i Fl =e REE PERE CREPES EEReeicciccr o 1s PREPRRSEECCEECCeeeE ER Ceceeey J) Perec ErEEE CES eC cre cer er er 5} FEEEEIEEEEEEEENC EERE EEE aE GRRE EEE EEE AREER HEEE PERE V4 q (| ACEP ya 5 Hr S a Wz ee BQ) EEEEE EERE ECE ECAC EEE a TEs fof lL bish haha enflas an fen| af anefan a sof en fun | faa fon fal S = PERRIER ESHER ARSE | O & A berrerecrereeerecceeeeyeeceecere & Bo) Fee Re seeeeeeeee eee SESE sf EREEERCEREE EERE ECEEENE LIE oe Se ea) ali Lj BERR EERE EEE CSN cE) \ 2) BEEEEREE Eee CEREEREEER SEE) ea 0 M EEE fasts at|sfataya stele i ss i 7 PERE IEEE EEE EEE EEE Eee eh yt ee es Too. 6 Sg 8 8 oO a © Ye) ~ o a a o a, 4 8 SIHONI NI NOILOVULXT meee Ronse fomverd —. Heeneth teed ieee tesa ket deena FORM 222-B LOAD,POUNDS (x1000) ZF a |_4” NA PROPOSED SUBSTATION rwe a x CENTER All , MERIDIAN RIVER / COPPER roe y S PROPOSED G : 138 KV j a TRANSIMISSIOM coat > LINE STATION G 3 No 12 SUBSTATION ra Ke | ZONE I. U j ra > Precis 4 \ oF ; \ TASINA PROPOSED \~____ periods Or 1's Ivacons MEALS rrerminls Orn SUBSTATION roar Ss Thompson i Joes Poss i F es Nsozomon GULCH PCRS 14. 4/24. 9 KV DC LIGHTNING FEO TESTA - RAE R2ZE RaW GENERATION STATION Row | orsw Lraw ~ MINER ANO WINER [Vi COMSULTING ENOINEERS, INCONPOSATEO R3W R2W « CROMADS ee eee = = ee aetna ee sits ee = $+ -u JOB NAME JOS NO. age TESTS G7-G SHC, ToG. A. Uet E2ocn | DESCRIPTION | OES BY: DATE PLot PLAN STRvcTuRE G7-G| woe D-2- 81 7 RE-INSTALLAD AK CHER W009 21100 © e MOND CRT ese EETETOSNES CEMEKE TEE MORIE HIT HeRR ere were weer we a ee S my x U U Ry x O © | yoy : o-pepape- coneamenemeyeeene: amen em ann wollen pemewes ewe men er rater: 9:74! ae v en ( PLOT PLAN jy STeuc mite || eo y= ce | SOLOMON GULCH — GLENN ALLEN ‘Vas kV TRANSMISSION LINE EU ae ese Oe OU NEL 1 FISTS TSTSIED Jel Ts SSI eee eae eee ete ete £27 aS See JST Sei alealealy — — women UNDISTURBED -- EARTH en a ASSEMBLY UNIT No.[ TYPE - ie DIA.X 1/2, 13/15" HOLE 1 1 BA'DIA. X 10 O° 1 [SMALL DIA.=6", LARGE DIA. = 13 "HT | 2.0,000 LBS. ITE ot MATERIAL WASHER, ROUND : | | | | | | = | CONCRETE ANCHOR, “45° BEVEL 1 HOLDING POWER —— | I | Z | . | 2 . . ANCHOR ASSEMBLY [L i 20,000 POUND LOAD TAs =e reenninageney—en Se SS a te EIT ESET | | APPENDIX « a ait daesntaiimat enema eh Renacetett Reeve Boner doer = : EARTH ANCHOR TEST RECORD Fest No. / ; Project No. EL aCEHM L ‘e of Test ws i} -/ . Client Kye Dave Fito wehor Cat. No. Type Vbilés Mig. ae AveroR * ] L vation - 67-6 pee Angle o/s¢ Depth 7’ Date sustalied talled by HECU ME ElECTHYC urpose of Test MELE TON : ct LT --und Conditions faces Test Usk TO eA SOE SOK PULL TEST RESULTS =" tem Time Notes and Comments ——1, Pull] Load Scale Creep Pounds Reading Inches (IN) SV | oO q =e. <3 a fue 10% \ Vy GiFO [F000 LI 2 Vy WAS 12000 Lbs DY Gis {125 iS. | 2%, | me | meme | ees | eee | mmeey | rr - Gi. ae ae 10 OOD : poig "| ata Ly 7 Ye. li ae SEKCKM PY 5 LICK LYM Rich Mw . TE) STEWSKO ibserved by: Bexotenms (ick Urey By esrahorl : TA? STEELE f . Photo Numbers: comments: i}: 2cort hv: # = : . Ranwavad hue L- » EAKIH ANCHOR TESI RECORD [ st No. Kk _ : Project No. -@ 2OG i ec > ate of Test 5 -~/S~ &/ Client R&C FORO A chor Cat. No. Type SLUG Mig. [escription_ _AMcyoK = 7 L cation 67-¢& : wows Angle “/s* Depth ret Date Installed nstalled by AG@KDUW/z Ble ems : F -pose of Test INS A Ti 7 J round Conditions during Test 4 wie TT miueser a CKAELY PULL TEST RESULTS Scale otes and Comments Reading (IN) Pull Load Pounds N Creep Inches EPFL LOO {ors 7—T JoGo0 SWE TTy7 hor 37 | jocvoa TSSE [t/2” fin. S| focos TIL é i We” j- | EELY LORD a Oras Bere lox | 62/7 | 2” O/Sa isScoa é" Sie 7 j IQiSsS 1SCOB EME77 3 a AFFL? CORD 22S > 3 3 fe 7194000 Gi 4PFLY CCAD oy S COYTIMUDUS FUMAYYCG_TG MAW THN L029 ARCHOK MOVEMENT COV TV UOLS | | s | i ior mee I | | L Pa i af iz imum Sustained Load § 000 lbs. Maximum Pull Out Load /9 000 Ibs vipment used: — AAV CHER ESTER. p= by: _SEKCH MAYS CHEK, Ly Wn/ Rieumed , TI? 5 TRU/AKO Yb erved by: Brecnmavs Wik, LYVY Kiehmnv, THO sTEUIAKO i . Photo Numbers: 20 yents: ej rt by: pone epee Approved by: EARTH ANCHOR TEST RECORD “est No. \ . Project No. - vite of Testy > fh i Client AS02270. Anchor Cat. No. Type SLUC: Nig. icription PLACE FG L cation - GT & fnstalled Angle Y5° Depth 7! Date tate tet 1. italled by BAKOLINE FE UECTAIC Purpose of Test MMS fzcTI6WV S | uund Conditions during Test MUso¥ CAVE Der PULL TEST RESULTS iF | Time Pull Load | Scale Creep Notes and Comments Pounds Reading Inches Cy : [ -Wi37 O SY7/ Os be iL - t THE LLY CCAD Wi @O SOOO i SPR Vf i EES FOO SY x Wey | x | PEAY PAD Wide — | l000G S YE Se g His? | tena | é BY j {i S& | /oesa G 3/7 : | EB 092 COG ERS {SGCo TY. YS : j | {2760 1S000 G2. + “4/4 | COMTVM RS fA NPY LIA EG I | TO Sf IUPLM TPA LCV? LYVOGQE PACE LED 7 t t Centra oS AF _/SCCdLE4E | E | Jt ft] ' ree peered i¥eximum Sustained Load IS¢ CHO lbs. Maximum Pull Out Load f#SOCXDd Tbs i ipment used: PAVCHCR, TESTER. 3 rs ] ted by: BEKP MENS LOIK, LYRA RICA Me, TROD _ STEW é Cc by: KEK MAYS (lk CYWN RicBenr fl DH STAVRAC ti. Photo Numbers: comments: ee. ’ EARTH ANCHOR TEST RECORD re No. +f Project No. _E20Gi _ 2te of Test 5- IS —~F/ Client ARIA EREALE Sr hor Cat. No. Type CLUG Mig. Eererton DNV CHR #2 ¢ ation G 7-6 Fustalléd Angle YS2 Depth 7 Date sneer : [ “stalled by § HYROUME BLECIKIK Pu pose of Test IMs AxcTIOnV vk j ound Conditions during Test Mwepy £ 6KAVEuY PULL _TEST RESULTS — Time ; Pull Load Scale Creep Notes and Comments ° Pounds Reading Inches * (IN) ; [PYS & 12' @ SEEC Y“ LOA VK SOOG 2-4 _| YER L. ARKLEY L0ALS 1{57 | SOOD | 2y_} CHK} Fi SC | SOG | 12S 2 A = Ye _| | * | veouey were eae conan Mianaei ll Raseme! SW (O26G Tre Lver” fo2 0006 “Wve ‘Fiz | DOU. ICOCO UV 1G. | i | FLO LOAD ES 1c 1Sceo /0” DY. | COVA Ao eet 2s ISCoo f Gf | B3%a"| i ‘[aya9 (s0ce Qe 3 he “4 E {2:2 [JOC SVL Dt | CENTIMUOUS —SAQVENM RN I | | | WWAKCE TO Gey Asove ile | 172 OAOLL : | [ : | : I wa iM | | 1 i Hl ] | ‘| 1 | wa.imum Sustained Load |[SOOO lbs. Maximum Pul) Out Load _)° } QOo00 Ibs. ] vipment used: ANCHOR TEsTHe Wpoted by: BERG ANS WICK, Leni KICBMAN, TA STELIAR sboerved by: BERCHMAYS WICK, LYM _RICeMiv, TP STERIALP { Photo Numbers: bo....ENES : 1 7 pert by: Approved by:. “oe a a einen pee Gee a ee a alo “2st No. = . Project No. -E2O6l/ vé e of Test F-1S-.E1 Client RED? POL? tnchor Cat. No. Type SLUG Mfg. ? cription ArvClok, FS “< ation. Gy-~ © ; wtalled Angle YS> Depth 7! Date ysis 76h ly talled by _ HAKEUNZ ELE CIKIL Purpose of Test _INSFECTIOY 2" i . ind Conditions during Test MUIOY GRRVEWY Dig | : ° . PULL TEST RESULTS Pull Load Scale Creep Notes and Comments Pounds Reading Inches (IN) oO I2%e"| _O SOOO Wee" | 77” PLY LORD SoCo tL) Ss” WLS ee ZoAS 10GOO Wve | te” 1GGO0o Li Lf Phe | joc0o LL LHe? | IrCC PY LOA [sooo 1G afe | re" tsocn | (o'/y | 1 Ye [soce | (oY | ft '7é | | TWEE LOAD [9 00U i/o | 2ZWwH | [4¢6oo SVs | RIYCe"| Cowrmuos Moavem=7— - [AS Lofo [Ss FPF URO | r CAV) GE7F-ABIVE /P000 | | | | | [ | } = — | L ; (pximum Sustained Load /SOOS bs. Maximum Pull Out Load 170% lbs { pment used: _ A*VEHOR. TESTER . . t= J ed by: GERcymrys LIK, LENAl RICUMI TAO STEzLINSO a by: DBRCHAAND (I/CK, LY AA Lic (}taay TItO STEWARD - Photo Numbers: (ga rae : “EARTH ANCHOR TEST RECORD F2.t No. G = Project No. - ~ 2OLM/ lat of Test F-/S-F/ Client Aa THEXFORD \n yor Cat. No. Type S¢UG hig. | 2scription BEINSTZKLED AVMCHOR. -0 tion GT7-G Prscalléd Angle “sev Depth a7" Date Installed ©@~-/S -5/7 la-talled by JMLE STEESY CF PE THER POCO ru dose of Test (MSKECTION [ound Conditions during Test Wer ¢ MWg7Y PULL TEST RESULTS Scale roo Time Pull Load Creep Notes and Comments be Pounds a Inches Pes IN } oO | 6% | Oo [ | [ ot Ve = | S609 | 65% | 3h [ | Sa0o | 6% x bs { SCOOT 6 EH/c Ys | ] { | i HYfL © LOAD | focao & | 7/77 L- FOC 6 VY, & | ae COC > Ake | : | FES LOAD : 75000 SG. _| [7 _| es | [S000 | SY | ive | [S000 S Ye [4 Vr AT QOCEO SH | [47a 3 20000 SLE / f ae | O000 | S$ %, / eT = | | = IFFLE LORD a ZS006 YA | 2% | | 25660 YR \ 2ye | [- | 25900 | SV2 Paez a | [: I | pximum Sustained Load SS5000 lbs. Maximum Pull Out Load FIOORO lbs. Fpoent used: Arto R. WES TEX. : [sted by: _BeXCH Mays UNCK, LY RICH MAY. TO S7RELMILO pserved by: BEKCHDAAMS GIUCK, (3A AICHMAS T2722 STEULICO &j “Photo Numbers: onwents: port by: 1 Approved bye bo. ; EARTH ANCHOR TEST RECORD a No. b . Project No. -E20CH/ ate of Test S~/s -*/ Client RET HPSL OOP A chor Cat. No. Type SCUG Hig. escription R2I4S7TALLED AAC Ho Li ation - G7-E ate Angle 4ys° Bepth|.| || > Bate Teetatied ||) 6 -1es e7) |||!) Lctalled by YALE s7evBr OF RE THE FOLO | P -pose of Test /AS¢ECTIONW mi [ round Conditions during Test WeT ¢ muUZlYV i PULL TEST RESULTS y vem Time Pull Load care Creep fai and Comments ir Pounds ve Inches ' IN ' | Av7LY LOAD i iff eg eee | ee ee = | 5 TIA 3B¢ SAL 2V%e i | i | RAL y COAT at FWi25 | 35000 (size Sit I i 12E | 35000 3/2, [ 3 34 : Ti33 350K? By 3 Ke 7 : il BUTT i TELE LOAD Tiss | aoOoo 7? SiH COMTIMCOOS PAQVERAENT— { | | COYTIVSRIS LEDS OAL, he | | | TO fay PIV L000 CS [ | | | : ] | | | a | | L. | Pie [ | { | | | | A _ | | | | “i | | i | I L il | | nie | | | | | i I [ | faximum Sustained Load .3S5000 lbs. Maximum Pull Out Load _S/0000 _1bs ~ipment used: ANCHOR. YESTEX. ; ae by: BERAIMAYS CWCK TNE AK NM Ae TA STZADO Pail by: Bea mays Ur CW RK MA THD? STEW PT % . Photo Numbers: conments: epurt by: i Approved by=_. at Renee eee mR NOTES _ 2 2% 37 AAD PIDA-LCAPACLIY.. WY orRAULIC CYLINDER ~ -AVO FRAAIE £0,000 POUNDS. ‘2. ANQCE oF AN CH ore 7° BE TESTED -. Tes PAGS Fp. 908 a —— an ans - - B--ANLAY ore -€XEBoey grange eo" "FROM. “oe AG ROLWP.CEVEC —— ——= TIE WEIGHT OF FRAME YANO HYDRAULIC . we - CY CIN PER S95 PowNVWPS AIAXIMUN... ---.- =e /5.-PROVASI ON FOPR SLING ATTA CYMENT . = = OF FSXTURE TL EIX TURE CAW faapett BE OS ASS EPIBLED. ~ FOR, EASY FRANSPORTATVON ...-—---. -- —7. €ARGER PASS nTAY BE PROVIDED IF — BHYCH.SS REPYVRED BAY GROLNP CONDITIONS | DBA KDORAVYLICE CYLIW PERT OPERATED BY I HAND .PUNIP WITH PIRECT (REA DOU LT : x -IIN KES PS EO KIPS ADAXSANUA- : — CONTRACT NO. = ~~~ VAN GULIK & ASSOCIATES, INC. sow |2-¢-94 LAKE OSWEGO, OREGON . LE PoRYABRLE EARTH ANCHOR VTesT FIXvTYVRE IPS STE eis l60,000 LBs. MAAIMYM,- FRAC- DECIMAL - ANGLE | SIZE : , ‘ TION | x |23| XXX + |B | Roc4- BAe = _ z .03 | = .010| O°—30' [scale H “= 7 & O” | sHEET os - + ms Lilie te || Is ; 1) TORQUE WRENCH _ || Lee hie | Pee Wi : Wie, Fee Rody Te HT fat lee Bele eu ey towne “VULYE | _C.G...* ee “ : Dater pis isl te ; 7 1 5 Gg ggg LNG is =|t-|4-/-+ —|-|-|-}-}-1— meen lf ADT eee yoy ree od ood ! 1 + pasmme * penney ° gue SGU pa BEY yen Naan i ‘ ae, LOAD Tae | O13401- 11 ~ Li eA al _FIE 28 PHOTOGRAPHS Photograph No. 1 Front view of anchor testing fixture during testing of anchor No. 5. The reference scale is fastened to the anchor and movement of the anchor is measured from this scale with a stringline supported by two stakes. Photograph No. 2 - Side view of test setup on anchor No. 5. The red hose connects the yellow hydraulic hand pump in the background to the hydraulic ram in the cradle of the fixture. The chain restrains the anchor fixture from moving due to the lateral force components parallel to the ground. — Seemed — | | | I | l NEGATIVE NO. E206P169 PHOTO NO. i ; l L Photograph No. 3 Testing of anchor No. 6. In this instance the two front legs were blocked up to level the fixture. Photograph No. 4 This photographs shows the two stakes used to hold the stringline against which the movement of the anchor is measured, utilizing a reference scale clamped to the anchor rod. ey peas pean Fosenea pot pany ay yraoccy jose pone woe — — NEGATIVE -NO. E206P164 rag: ry pete, aes % Ee ha ty Oe s wa PHOTO NO. Form 2234 Photograph No. 5 This photograph shows the test setup at anchor No. 7 as the engineer is taking a movement reading. Also shown are the stakes supporting the stringline. Please note the unevenness of the terrain surrounding the anchor rod. Photograph No. 6 This photo shows the test setup at anchor No. 7, viewing down hill. This photo also shows the force gage displaying the pull-out load applied to the anchor. NEGATIVE NO. _ E206P162 NEGATIVE NO. E206P163 PHOTO NO. PHOTO NO. Form 223A Photograph No. 7 This photograph shows the test on the reinstalled anchor. The soil and weather condition made the test a real challenge. Photograph No. 8 This picture was taken during the test of the reinstalled anchor. The test engineer closely monitors the test as it progresses. NEGATIVE NO. E206P173 Bee Se FS Soe a Siew a Beene py ee = eas Sten ies PHOTO NO. | NEGATIVE No. E206P172 8 | . Form 223A RST Pea maw Dene Becca Bee Rory run re ini WS ed GRAY wu Rag PRy rere RE Hav RPACB 9 Ri APPENDIX C TRIP REPORT OF NANI G. BANERJEE - 30 SEPT. 81 Sept. 30, 1981 (Wed. ): Departed Anchorage: 8:00 A.M. Arrived Copper Center: 10:25 A.M. Departed Copper Center: 10:30 A.M. Arrived Valdez Airport: 5:00 P.M. Site inspection of 138 kV T/L by chartered helicopter along with Dale Steeby of IECO. Met Ken Alles of M&M at Copper Center and got him on board. Flew along the 138 kV T/L line from Copper Center to Meals substation. Closely observed on the ground some typical transmission towers representing different foundation conditions as below: Structure 99-1 (Piles structure) southside of Squirrel Creek near pipe line structure No. AS16-2 (#195). Ken Alles (M&M) agreed to provide IECO test pile data for analysis. Structure 68-2 (Guyed with TA 20C Anchors) Near 5lst mile. Angle structure. Anchor rods marked at ground level. No movement recorded. Structure 56-3 (All rock anchors embedded) 7' to 9' in rock. (Schist), medium hard with discontinuous joints. one rock anchor (9') did not move with 31,000 Ibs load. Guy wires snapped. Also checked with Chance's soil probe the soil overburden thickness near one anchor. The overburden thickness was found to be 2’ to 2.5' Structure 51-1 (Guyed with TA-10C and TA-20C anchors). Located near a small lake. One TA-10C guy wire was somewhat loose, not critical for the stability of this structure. One TA-20C anchor moved by 5" to 6" during construction. M&M reinforced the stability of this structure with 3 additional TA-20C anchors at this location. CVEA 18/g1 i * weer tao ney peay mewne porns Bor. Vang poeonin a | ag WE Structure 38-5: (Near Bear Creek) Angle (50°) structure. Guyed with TA-20C soil anchors. This structure is located within the flood plains of the river, thus the anchors are located below the ground water table. During flood time, the entire soil overburden above the anchors will be submerged. The soil type at this location is gravelly, sand/sandy gravel with very little or no cohesion. We could drive Chance's helix soil probe to a maximum depth of 2.5' and the recorded maximum soil resistance was 150 in-lb. The probe could not be advanced further as it started spinning possibly on a piece of gravel. At this location, sagging was done in Sept. 1980 and so far, the anchors have not moved as established by observing the tell-tales which exist on some of the anchors. These observations are not adequate to confirm the adequacy of these anchors. For the same size (18-in diameter), depth (6.5 ft.) and inclination (45°), these anchors installed in loose to medium dense sand and gravel will have significantly smaller capacity compared to that installed in undis- turbed glacial till. We plan to reanalyze the capacity of TA-20C anchors installed in cohesionless sand and gravel. (See Fig. SK-1 enclosed). We saw from the air some digging in progress at a transmission tower structure along a river section not far from structure 34-1. According to Ken Alles, this transmission tower is being redesigned/relocated. Concluding Remarks: (1) We did not see any visible sign of distress of the guyed anchors during the field trip. (2) In many locations, M&M installed additional soil anchors to reinforce the anchored towers. (3) No anchor movement at the structures visited were inferred from tell-tale marks on anchor rods. (4) Locations where soil anchors are installed in cohesionless sand and gravel like Str. 38-5, anchor capacity will be about 1/3 of that in glacial till as at Str 67-6. Either proof testing or installation of additional anchors are recommended at those locations. CVEA 18/g2 ea RET | TY Baad wera Rwy preg tt BRREN you StU | Sy a (5) (6) (7) (8) Rock anchors “as-built" are embedded 3' to 3' inside medium hard rock with discontinuous joints - thus better than that shown in the spec. drawing. Rock anchors (TA-2H, 35,000 lbs capacity) which are embedded less than 9' inside medium hard rock should be proof tested or additional anchors installed, based on actual guy loads. M&M has been requested to provide "as-built" rock anchor drawing and specification Ken Alles confirmed that incorrect soil anchor installation as found at Str 67-6 is not typical for other locations. M&M agreed to provide test pile pullout test data to IECO. This data was used for designing piles in permafrost zone. CVEA 18/3 chen and associates, inc. CONSULTING ENGINEERS SOILR FOUNDATION 98 S. ZUM} . DENVER, COLORADO 80223 . 303/744-7105 ENGINEERING. “ June 29, 1979 SubJect: Foundatlon PIling, : 138KV Transmisston Line, Solomon Gulch-Glennallen, Alaska. Job No. 18,667 Mr. Doug Proctor Miner & Hiner epee eine Engineers 912 - 20 Avenue Greeley, Colorado 80623 Gentlemen: - As requested by Mr. Doug Proctor of Miner & Hiner Consulting Engineers, !nc., we observed driving of steel pilings near Glennallten on June 20, 1979. The purpose of the driving of test pilings was to determine If sufficlent penetration could be obtalned Into the perma- frost with the steel piling utilizing a low energy, high frequency hammer which Rogers Electric has used In Alaska for pI}Ing selection on other transmission lines. The test pilings were driven approximately 250 feet north of the — northwest corner of the Athna Lodge. The lodge Is located east of the Intersectlon of the Richardson and Glen Highways. The only subsof] Information which was avallable Is a log of Test Hole No. 2, drilled and logged on Apri} 16, 1975 by R EM Consultants, Inc. A copy of the tog is enclosed. The log Indicates 24 feet of nonfrozen, sItty clay over- -lytng frozen sandy silt with gravel and sandy gravel with some silty clays to the depth Investigated, 33 feet. In total, three test plles were driven at the referenced locatlon. Piling No. 1 had been driven to the terminal depth of 17 feet and Plling No. 2 had been driven to 17 feet and was being spliced on my arrival at the site. Pile No. 3 was driven 3 feet north of Pile No. 1. Pile Nea. 2 ts located 30 feet north of Plle No. 3. The piles were driven In natural terratn which consIsted of a sparse growth of spruce, aspen or birch trees. An auger drill with the capability of drilling 10 feet was avallable at the site, however, It could not be mobIl!zed to the area of the test plles because of damage to the terraln. Approximately 15 minutes after completion of driving Pile No. 3, a pullout test was performed. A load of approximately 2] kips was placed on the pile for three minutes. No movement of the pile occurred under this pullout test. The flanges of the No. 1 ptle were bent during driving. No. 2 and 3 pllings were undamaged during driving. The pile driving records are enclosed. a an ee Le eee, — Hr. Doug Proctor MIner & Hiner Consulting EngI neers June 29, 1979 Page 2 Driving Hammer: The hammer used to’Iinstal] the referenced p!ling was a Hodel by Hy-Ram which weighs 1600 pounds, has an Jmpact of 1,300 foot- pounds per blow and delivers 450 blows per minute. This hammer Js hydraulfcally operated and Is not marketed for plle installatlon. Although the hammer Is not marketed for pIle driving, commerctal alr and steam-driven plte hammers with low Impact energy and hlgh number of blows per minute are avallable with energy and welght similar to the referenced hammer. The 88 Hy-Ram hammer Is compatible with driving 8-Inch by 31-pound plling of lengths up to 40 feet. This compatibIItty Is dependent on using relatively thin wood cushions or an artificial cushton of Mycarta with higher modulus of elasticIty. The smaller sectIon of pile Is the most deslrable considering the slze of plle driving hammer. The observation and record for driving three pllings certainly does not provide sufficient geotechnical Information for providing driving criterla for 55 miles of transmission line. The depth to permafrost within 30 feet between the pilings varied from approxtmately 34 feet to 1) feet and the penetration resIstance across a short distance Is also extremely erratic. A further complicatlon to the evaluation is that according to the Environmental Atlas of Alaska, a portion of the 55-nlle section of the proposed line to be placed on pilings wlll be In-areas delineated as "'generally underlain by continuous permafrost" and a portion will be in the area delineated as "'underlain by Isolated masses of permafrost". -We do not know the criterla used to select the portion of the transmisston tower to be placed on driven pilings. A review of a drawing provided by Mr. Yivisaker of Copper Valley Electric Association entitled "Solomon Gulch-Glennallen, Alaska, 138KV Transmission Line Right-of-Way Application Map't (8 sheets) shows the allgnmant with respect to the Trans-Alaskan Pipeline. This drawIng Indicates portions of the pipeline which are burled and above the ground surface. It Is my understanding that generally the pIpeline Is buried where stable conditlons were encountered. In areas of permafrost, stable cond! tlons would be considered at locatlons of shallow bedrock and solls non-susceptible to frost heave (gravels ahd boulders). We understand the transmisslon line to be supported by driven pilings witt be between Station 2855 and Station 5760. Along this reach, there are substantial distances (according to the referenced drawIngs) the pIpeline Is burled. Host notably, these reaches are from the beginning of the driven pile Installation Statlon 2855 to approxtImately Statlon 3840. This constitutes the southern portion of the IIne to be supported on driven p!Ilings. A substantial span In the vicinity of Stations 4515 and 5160 are also burted. The reason for subsurface construction of the Hr. Doug Proctor Miner & Miner Consulting Engineers ‘ June 29, 1973 Page 3 pipeline Is not known, nor Is it known whether the line Is refrigerated. PossIble reasons for not buryIng the Ifne are that bedrock was encountered at shallow depths, gravel and cobbly materlal not susceptible to frost was encountered, or no permafrost was encountered. We understand maxImum pllIng depth supporting the pIpeltne Tn the reach under consideratlon ts 80 feet. The erratic conditions at the Athna Lodge sIte, varlable conditlons along the pipe alflgnment, Judging from the Environmental Atlas of Alaska, and pipeline partially constructed below grade and partly above grade supports that a wide range of subsurface condItlons existing along the SS-mble alignment. Geotechnical and Subsurface !nformatlon: We understand no geotechnical or subsurface Investigation Is planned along the proposed transmission line. We further understand If monies were avallable to perform geo- technical exploration, that timing of the project would not permit. “While In Anchorage, ! vistted the offices of Alyaleska Pipeline Service for the purposé of obtaining geotechnical Informatton along the existing pipe line. I! contacted Engineers Dave Willlams and John Farrel) to discuss the posstbl tity of receiving subsurface Informatton for thls alignment. They Indicated that geotechnical Informatton was avallable on a licensing agreement which would have to be worked out through Alfred T. Smith, senlor attorney for the plpelfne. Itnformatton which would be helpful Is as follows: 3.1.3 “Landform Profile", Reviston 1; 3.14 "Bore Hole Logs, Trans-Alaskan PIpeline Route’; 3.2.4 "Geotechnical Mode, Conftrmatton Bore Hole Summary"; (1) Therma} State (2) Soll Type (3) Percent Vistbalized (4) Cobbles and Boulders (5) Landforms and Type 3.6 "Geotechnical Data’; 3.6.3 “USM Logs''; Hr. Doug Proctor HIner & Miner Consulting Engineers June 29, 1979 Page 4 3.6.2 “Trench Logs"; i 3.6.3 "Nuclear DensIty Tests" | am sure IIcenstng of this Information will be expensive. The above list Is made wlth the least detall I!sted first wlth progresslvely more detalled tnformatlon through the IIst. Scope of Work: We understand our scope of work Is to provide ptle driving criterila which can be used durIng the Installation of the pIitng which will provide a minimum of risk for foundatlon movement after completion of the transmIsston towers. Without detalled Information on the subsall conditions, only general criterla can be discussed with respect to methods of minimizing risk of foundation movement. In order to proceed, we wlll need the following Information on loading conditlons: (1) Long term loads (loads from dead welght of tower and transmIssion line). (2) Maxtmum loads expected on pilings, both uplift and vertically downward. The source of the Joads, duration of the loads, and time of year loads are to be expected. (3) Intermittent loads larger than the dead loads which may be on the plling for stgnificantly longer perfods than the maxImum load. } wlll be contacting you the first part of the week to arrange a meeting where we can have an exchange of Information and more closely deftne our scope of Involvement. eta / Sincerely, PSHE », CHEN AND ASSOCIATES, INC. i oy DEB/med LTRS Enct.. We woven We ean : g By < J Zé sit Donald E<Bressler, P. E. PILE DRIVING RECORDS Piling No. | HP J0 x 42 Total Driving Time: 40 MInutes Permafrost Estimated: 3% Feet Time ‘Depth ; HInutes Seconds V-42 1 4S 12-13 2 30 13-14 5 = 14-15 7 ks 15-16 5 == 16-17 6 -- PillIng No. 2 W8 x 3) Permafrost Estimated: 1] Feet Time Depth HInutes Seconds 13-14 - 15 14-15 : . - 25 15-16 * - 30 16-17 - 25 17-18 7 - 25 Stopped 45 minutes to splice plle . 18-19 = 55 19-20 1 55 20-21 2 20 21-22 2 20 22-23 1 45 23-24 Zz “3 24-25 2 4s 25-26 2 50 26-27 3 0 27-28 3 15 28-29 4 0 Piling No. 3 Total Driving Time: 20 Minutes Permafrost Estimated: 3% Feet 3 MInute Pullout Test at 21 KIps - No Movement Time Depth : . Hinutes Seconds 0-6 1 0 6-7 = 20 7-8 bo 20 8-9 - - 30 9-10 ~ 35 10-11 me ks ti-12 = 50 12-13 = 55 13-14 2 10 14-15 2 45 15-16 4 -- 16-17 4 -- 8 9. ®& chen and associates, inc. CONSULTING ENGINEERS SOIL L FOUNDATION 95 S. ZUNI . DENVER, COLORADO 80223 ENGINEERING . / . - July 23, 1973 303/744-7105 “Subject: Pile Driving Criteria, 138 KV Transmisston Line, . : Ff Solomon Gulch, Glenallen, . be Alaska. _ Job No.” 18,667 . Mr. Doug Proctor Hiner & Miner, Consulting Engineers, Inc. : 912 - 27th. Avenue : . x SS ° P. 0. Box 548 , Greeley, Colorado 80632. Gentlemen: - From our meeting at your office on July 6, 1979, we understand the following maximum tower loadings are anticipated. . Dead and Line Loads = 5.6 kips Dead, Line and | Degree Deflection, Loads = 6 kips Dead, Line, -] Degree Deflection and Wind Loads = 10.5 kips . Dead, Line, and Ice Loads = 18.1 kips , Dead, Line, Ice and | Degree. Deflection Loads Dead, Line, Ice, 1 Degree Deflection, and Wind Loads = 30 Kips . We understand the transmission lIne would be installed during the winter months when the ground surface Is frozen and snow covered.” The reason for the winter installation is to provide access over soft ground and to minimize the damage to existing terraln. The preservation-of ‘the existing terrain is particularly important for the pile foundations penetrating the permafrost. Disturbance of the tundra and other ground . cover which provides a stable permafrost condition is of utmost importance, Subsoil and frost conditions will. vary a great dea} along the . ,* 55-mlle alignment proposed for pile foundations. We foresee at least three quite different subsoll conditions occurring along the line. They generally are permafrost encountered at varying depths, no permafrost encountered with soft soils underlying the upper frozen ground, and no permafrost being encountered with relatively dense solls underlying the upper frozen ground. These conditions will be discussed individually as follows: : Hr. Doug Proctor iesDieare ley HIner & HIner, Consulting Englneers, Inc... a July 23, 1979 | ny m Page 2 tel "7 x Permafrost Encountered: We belleve thls Is the cond!Itlon encountered In the test plling driven at the Athna Lodge on June 20, 1979.- Research in Indicates that tangential adfreeze strength of ice and permafrost to steel plling is dependent on temperature of permafrost and duration of loads. -As temperature of the permafrost decreases, the tangential adfreeze strength increases. The tangential adfreeze strength ~ decreases with sustalned loading. The decrease In tangentlal adfreeze ' strength from short-term’ loading to.long-term loading is as much as. 90 percent.. For this reason, we do not belleve short-term pullout r ‘ tests for plles installed in the permafrost will be indicative of ' bearing capacities Pears — the. “Pi roposed transmisston Vine. The practice of eutating 2 feet and sometimes 3 feet of- penetration Into permafrost for each foot of active frost layer is widely used. Based on this criteria, and estimating the actlve frost layer between 4 and 6 feet, we have evaluated the W8 x 31 pile penetrating permafrost 12 feet. -Thls should have sufflctent.depth to resIst frost JackIng of the plle- provided the ae regime in the permafrost is not disturbed; Fig. l_presents a plot of plle loading vs. required tangentlal adfreeze strength with 12 feet of penetration into permafrost. The.. adfreeze strength required to support the maximum load under dead, line, and 1 degree deflection is approximately 0.9 psi. The adfreeze strength required to support the dead, lIne, 1 degree deflection, and ice loads is approximately 3.5 psi. Although we do not have access to studies with loadings on the order of | ps! tangential adfreeze strength, we belleve only minor creep and settlement will occur under this long-term loading. . Under’ long-term loading at’ 3.5 ps! tangential adfreeze strength experl- ‘enced under Icing conditions, creep on the order of 1 inch per week may be expected. This creep may not occur If.a portion of the upper active soil layer Is frozen. It Is not known whether the ice condition can develop at a period when the upper actlve layer Is unfrozen. No Permafrost, Difficult Driving Solls:. This condition may be encountered. when gravels, cobbles, boulders or bedrock Is encountered. There may be cases when the hard material is encountered near the surface or when It Is encountered at depth. ‘If these condItlons are encountered, termination of the pile utilizing driving formulas may be used. For the proposed piling, wou! iTV Gece a 2 sorethe penetrar iO Tg $29 aS = Tr cos = 1 odei ; 3B Tas Oz biogs : f ~ Nr. Doug Proctor ly Ri : Miner & Hiner, Consul ting EngIneers, Inc. July 23, 1979 Page 3 the ultimate capacity of the plle as calculated by the EngI neering News formula Is approxtImately 150 kips. The factor of safety under the - extreme loading conditlon Is 5 rather than the traditional 6 for the Engineering News formula. The uplift resistance for thls piling cannot be calculated because depth of embedment or soll type for the upper solls are not known, : Soft Driving Piling Without Permafrost: In thls condition, we would anticlpate = Tozen ground near the surface-and no Increase In driving resistance thereafter. It wlll be very difficult to estimate the capacity. of this plling iby, driving formulas because most of the reistance may be provid th Lkozen material which will thaw durlng warm seasons. ets Zrecanmend: topping: a = ; B-: . this penetratlon Is not a, cnsideration of driving additlonal plles should be made. Fig. 2 shows the average adhesion required between’ the H-pItes and penetrating solls vs. plle loading In klps. These graphs have been calculated for 30-foot and 20-foot long piles reflecting factors of safety of 1 and 2. Ordinary range of adheslon values for soft:clays and slIts vary from 100 psf to 600 psf. In areas of soft driving, we recommend a minimum of 30-foot long piling. ' Agaln, we do not know whether the higher loads caused by line icing can be anticipated at times when the upper ground surface Is not frozen. If the upper ground surface Is frozen, increased pile capacity Is-available. «The jacking resistance for these piles Is. | Gene, equal to the vertical resistance, LIMITATIONS _ Our comments and recommendations -are based on the observance of driving of three piles near the-Athna Lodge, Glenallen, Alaska, of a log of an exploratory boring approximately 250 feet from the plle ~ Installations, and research of published IIterature. No geotechnical Information was obtained from the particular transmisston alfgnment. The above discusstons are based-on «the use Of a.Model 88 Hydro-ram for pile Installation and may not apply when other equipment Is used. The plle foe palebton aad be Ec aenial by 2 knowledgeable engineer~ Records for driving each plling should be maintalned and evaluated. tt is recommended that exploratory borings be made at selected locations to determine subsoll conditlons during the Installation of the pIling- The subsoil Information can be correlated wlth the pIle driving records of adjacent plles and projected to other pllings along the alignment. should’ be taken at the installation of the piling in permafrost to minimize the upset of the thermal regime In the solls- Care Hr. Doug Proctor - : rhs HIner & Miner, Consulting Engineers, Inc. July 23, 1979 Page 4 If there are questions, or if we may be of additional service, please do not hesitate to call.- i an Sincerely, CHEN AND ASSOCIATES, INC. Ss _ By (Ge ROWwee a * Donald E. Bressler, P. Es DEB/med Enclosures i Rev. By: F.H,.C. es T i 1 ‘ an = = { : = 2 q - wv 2 . c " 2A N ei i 4 - . ae an wee epee } _— Dead + Line <8 7. . ; : oy eae i + 1° Deflection J 3- z + Ice { \ - & L aa 7 - Lie o o 1 ‘ ii — : =" : Dead + Line’ + 1° Deflection . Yer = 3 : : a . oe = . a . . oe ’ : . e ~ 3 2 cA 0 ; Te * + er) 5 10: “15. t.4 . 20 25 30 Pile Loading in Kips | SF=2 SF] . (600) 300 (400) 200 z-Dead + Lire + 32 Defle thon + Ice (200) 100 Required Average Adheslon <|.2—-Dead + LIne + 1° Deflection De | 30-Foot, Long Plte tT T tr T 0 5 10 15 20 25 30 7 Pile Loading in Kips (600) .300 - v2e-Dead + itn + 1° Deflec tlon + Ice (400) 200 Requlred Average Adheslon (200) 100- > Dead + Line + 1° Deflection ~ 20-Foot Long Plle 0 25 * 10, 7 YS 20 - 25 30 7. Piieltoadina In-Kios ~~ LIL E LAI VING —- PEFPMAFPROST “fh i oO SOFT DRIVING WK PERMA FROST | AYver #hC A*77C1IS FONTS Wsfed bela have beerz achreved, the firral criteria rs fhart fhe last foot 4 piling r77us/ re s1sf af fie ira 100000 am 00.4 eae eomre a 1/25 LOUIS BAS DHE if pA O'2ZZ $ VPARP? . WT A SOLY Oniyo afi YD 112 Pid 2 DLOW ~ - 2 ™ een, Sen = RP verendiyes 3 tall se evensendidsoGabisd OGAENGN AG MIOTES 014 05%N 5 Vann Sw tesen pclal aS Ga anguebeatee Tee st et tet eee at ane % QS Blirpid (OU0 As s§oygf (1,1 OO) pI) PPO Q vk q PP? ‘fff SUYYLP AT 'AOLL/ OP fp SOL 0 es SAY WAe pls? fOOS f SO) BAP? tid B By PUD ys Ces. ULOVA DIA PUPA Hip LeipreU{ cites PCOF OF Bt1t ' ZLON Ey usas SILT Ey y VQ ys a vue'ssS 0 8 SS3age PR CVSENR : LONI? P1p vy By. ~ & WL LOYASLNO? SWE DY Nae cence fe wo ge ¥ ‘ , C2 O'2 GrVyours b x \ . fo. ko = ee ae es SS os) ans] Sd cos et] ee ee eee reel ~ J 1 ie a & “45> 2 ‘ ee ee ee ee J SSS Se tsrsSsrsitesssss a 2 \ . : S SQ. 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Ce -J Jo 2 |e eee oy ns & aera Jo 8 2 2 £0, ote b 3 10° 7 af oll 4s 10... a S 4 JO b Lae a Sel 7 5 6 on 10 is _& G 70. 4 6 o. 10 4 4 7. 0 3. 6 7. 10 5 2S 8 M0 | 2 6 8 10. ze me a2 70. oo. 6 9 lo t 4 SO 70 oO b lo ro o