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Wainwright Central District Heating & Power Generation Project Vol III 1982
WAINWRIGHT CENTRAL °:!<2 DISTRICT HEATING ....,,...” AND on POWER GENERATION PROJECT EXTENDED FEASIBILITY STUDY VOLUME THREE FEBRUARY 1982 as S arctic tec! services Incorporated CENTRAL DISTRICT HEATING AND POWER GENERATION PROJECT Prepared for NORTH SLOPE BOROUGH VOLUME THREE PRELIMINARY MINE DESIGN Prepared by Arctic Slope Technical Services, Inc. 420 L Street, Suite 406 Anchorage, Alaska 99501 February 1982 TABLE OF CONTENTS Page 4.01.0 SUMMARY AND RECOMMENDATIONS - MINING......... ebadesle alle 1-1 4.01.1 INTRODUCTION... . 2. cece cece cee cece cece cece bn tie 1-1 4.01.2 RECOMMENDATIONS - MINING........eee eee e coon ee 1-1 4.02.0 SURFACE MINE..... sbwelesdveieste le clentleahavoslbewse Lis sles tle 2-1 4.02.1 INTRODUCTION.........-ee eee eee eee ne aie metal ole 2-1 4.02.2 | PRELIMINARY COST CONSIDERATIONS... ..eseeeeeees 2-1 4.02.3 CONCLUSION............. lee He alent wclewslta ts ot osle 2-3 4.03.0 UNDERGROUND MINE....... We cles eliest ete cls sts at aa ee ue 3-1 4.03.1 INTRODUCTION........... ale tes Ps ealee le ts les fe 3-1 4.03.2 SUMMARY..... Sebel clic tle cb awech eh eels maleece inate 3-1 4.03.3. RESERVE ANALYSIS.....-..cc cee eee eee ccce cece be 3-2 4.03.4 MINE LAYOUT AND PLANNING.........eeeeeeeeeeeee 3-3 4.03.5 PRELIMINARY MINE COST ESTIMATE......--.---00e- 3-9 4.04.0 REFERENCES....... hele cbeveslee tests tee ws Bealn cele otlennets 4-1 4.05.0 MANUFACTURERS AND SUPPLIERS...-....eeeeeceeeeees Neale ole 5-1 APPENDIX A SUPPORTING DOCUMENTATION....-..eeceecccccecceccceces A-1 APPENDIX B MANUFACTURERS' LITERATURE. ..---eeeeeeeceecccecccccce B-1 pean, ne TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE LIST OF TABLES 4.2.1 SURFACE MINE — CAPITAL COST......2-.ee-0ee ee ceeeee 4.3.1 UNDERGROUND MINE - COAL RECOVERY CALCULATIONS..... 4.3.2 UNDERGROUND MINE - GROUND SUPPORT MATERIAL AND SUPPLY CALCULATIONS......eeeeeeeeee se ececcees . 4.3.3 UNDERGROUND MINE - GENERAL ASSUMPTIONS AND CALCULATIONS..... 4.3.4 UNDERGROUND MINE - CONSTRUCTION TIME AND CREW SIZE CALCULATIONS......-es-eee% eee ecccccccce ee 4.3.5 UNDERGROUND MINE - CAPITAL COSTS, LOWER 48, 3rd QUARTER 1981 S..cceeeeecceccccccccce 4.3.5A UNDERGROUND MINE - ESTIMATED WAINWRIGHT COSTS, 3rd QUARTER 1981 S..cececeeccecccccecccccees ecceee 4.3.6 UNDERGROUND MINE - MANPOWER SCHEDULE AND ANNUAL COSTS... cece ceccecccccsecccccecces eeccccee . 4.3.7 UNDERGROUND MINE 4.3.8 UNDERGROUND MINE 4.3.9 UNDERGROUND MINE 4.3.10 UNDERGROUND MINE MATERIAL AND SUPPLY COSTS...... ESTIMATE OF ASSESSMENTS......+- WORKING CAPITAL REQUIREMENTS... ESTIMATE OF FINANCIAL CHARGES... Page 2-4 3-16 3-18 3-19 3-22 3-24 3-25 3-26 3-27 3-28 3-29 3-30 LIST OF FIGURES Page FIGURE 4.3.1 PRELIMINARY MINE LAYOUT...........000. eet nal 3-12 FIGURE 4.2.2 PRELIMINARY MINE CONFIGURATION........-.eseeeees 3-13 FIGURE 4.3.3 ANTICIPATED SUPPORT REQUIREMENTS....... Se lll 3-14 FIGURE 4.3.4 MINE DEVELOPMENT SCHEDULE...........eeeeeeeeeee a 3-15 LIST OF MAPS Location MAP NO. 4.1 AREA A-B CONTOUR MAP. .....cececccccceeeeeeeuees Back MAP NO. 4.2 AREA A-B LOWER SEAM...... Eee eee Back MAP NO. 4.3 AREA A<B FENCE DIAGRAM NORTH...........0. Ble Back MAP NO. 4.4 AREA A-B FENCE DIAGRAM SOUTH.......eeeccecceceee Back 4.01.1 1-1 4.01.0 SUMMARY AND RECOMMENDATIONS - MINING INTRODUCTION Current literature on Arctic mining and on North Slope coal reserves is very limited. Available information was reviewed in detail and used to augment the drilling program conducted during the summer of 1981 as part of this study. Section 4.01.2 details the ASTS recommendations resulting from this study. 4.01.2 RECOMMENDATIONS - MINING 1. Adequate coal reserves are present near the village of Wain- wright to support a coal-fired generating station that could supply electric power and heat to the village. It is suggested that an underground mine best suits the project based on cost, reserve location, and climatic conditions. It is projected that operating and amortized capital costs for a small room and pillar mine to supply 10,000 tons of coal per year will approximate $73 per ton based on the assumptions detailed in Section 4.03.0 of this report. The grant for 50 ‘percent of the capital and the low interest rate on the balance are vital in achieving this cost. It is recommended that the mine be operated only during the winter months to facilitate maintaining frozen conditions. Capital costs for a small operation are very sensitive to small changes in life and tonnage. For instance, if the power plant only requires 5,000 tons per year instead of the design 10,000, total costs will exceed $91 per ton - all else being equal. A detailed training program will be required to train local labor to operate and maintain specialized underground mining equipment. It may also be necessary to bring in an outside expert periodically. iv2 A source of gravel for constructing an all-weather road to the mine has not been identified. This requirement should be met early in the project schedule. The selected mine site (drilling Area A-B) is based on only three widely spaced drill holes. Additional drilling should be completed early in the project schedule to confirm specific mine location. A detailed underground mine plan should be submitted to the Mine Safety and Health Administration early in the project schedule with specific attention to two areas which may require variances: 1) rock dusting and 2) dust supression without water sprays. 2-1 4.02.0 SURFACE MINE 4.02.1 INTRODUCTION The drilling conducted during the summer of 1981 located two areas near Wainwright which contain attractive coal reserves; Area C, approxi- mately eight and one half miles southwest of the village; and Area A-B, approximately one mile to the northeast as indicated on location map, figure 3-2, volume 2. Neither of these areas was shallow enough to be attractive as a surface mine reserve for a small tonnage operation. Area C averaged 70 feet deep and Area A-B averaged 130 feet deep. The coal seam at Area C is typically eight feet thick, which is better than A-B, with only six and one half feet of good coal; however Area C's longer haul makes Area A-B a rather obvious choice for an underground operation. Coal outcrops along both banks of the Kuk River. Areas were ob- served where strippable coal could be obtained (under less than 50 feet of cover). However, all of these locations would involve relatively long hauls and the problems associated with permitting, operating, and reclaiming a surface mine near a major river make surface mining appear to be an unrealistic choice. 4.02.2 PRELIMINARY COST CONSIDERATIONS Maintaining coal haulage during the summer season would require an all-weather road, which would be a major expense. It also appears that pit operations during the summer are complicated by water, mud, and unstable pit walls. It is recommended that a surface mine be scheduled for operation only during frozen conditions and that all coal haulage be conducted over frozen roads. ASTS previously submitted a gravel mining study to the North Slope Borough, dated September 28, 1981. Preliminary cost estimates are in- cluded in that report for an upland gravel mining operation. Overburden stripping for coal would be similar to mining gravel and pre-stripping for an upland gravel pit. Therefore, the upland gravel mining costs were reviewed to obtain preliminary open pit costs. Assumptions: 1. A suitable site can be located with 30 to 50 feet of overburden. 2. Mining would be conducted only during the eight months of frozen conditions. 3. An average coal thickness of seven and one half feet of good coal is available. 4. Mining recovery will equal 90 percent. 5. Coal density equals 1,760 tons per acre-foot. Calculations: 7.5 ft. x 90% x 1,760 TPAF = 11,800 recoverable tons per acre 10,000 tons required 11,880 tons per acre = 0.85 acres per year 0.85 acres x 40 ft. overburden x 43,560 sq. ft./acre 27 cu. ft./cu. yd. = 54,853 cu. yds. 54,853 cu. yds. x $3.24/cu. yd. (from gravel report) = $180,466 annual stripping cost after pit established $180 ,466 T0,000 tons $18.05 per ton for stripping only Preliminary Operating Cost Summary Overburden stripping $18.05 per ton Coal blasting and loading 3.29 per ton Coal hauling (eight miles) 10.86 per ton $32.20 per ton To this number must be added capital costs of $47 (see Table 4.2.1), permitting costs, any federal royalties and taxes, and reclamation costs. This high preliminary capital and operating cost and the fact that a suitable site has not been identified indicates that an under- ground mine may be more attractive and should at least be considered. A surface mine will be extremely sensitive to changes in tonnage; for instance, if only 5,000 tpy were required, costs would go from $79 per ton to over $126 per ton. 220) 4.02.3 CONCLUSION Based on the preceding analysis, it was decided to design an under- ground coal mine to develop the coal reserves at Area A-B. If the underground operation does not appear feasible, a detailed reevaluation of surface mining options can be made at that time. 2-4 TABLE 4.2.1 SURFACE MINE Capital Cost Depreciation Cost $ x 1,000 Life* $/ton Item (Lower 48 x 1.5) (Yrs.) (Prorated @ 10,000 Tpy) 1 Dozer D-9H 598 10 5.98 1 Loader 988-B 486 10 4.86 2 Dump Trucks 420 ea. 10 8.40 1 Drill 240 10 2.40 1 Explosives Truck 23 10 0.23 1 Personnel Vehicle 18 5 0.36 Subtotal 2,205 $22.23 Road Construction 8 miles @ $200,000 per mile = $1,600,000 = $ 8.00 (20 yrs.) Grader @ $ 375,000 and 10 year life = $§ 3.75 Subtotal: $1,975,000 $11.75 per ton Mine Shop and Warehouse 40 x 80 = 3,200 sq. ft. 3,200 sq. ft. x $75/sq. ft. = $240,000 prorated over 20 years = $1.20 per ton Total Capital = $4,420,000 50% grant and 50% at 8% interest Interest on $2,210,000 for 20 years = $11.46 per ton (calculated as constant payment mortgage loan) Total Capital per ton approximates $35.18 equipment sinking fund plus $11.46 loan interest for a total of $46.64 per ton. * The equipment will have low hourly usage per year but the severe climate and unskilled personnel will limit the life of the equipment. If equipment is used on other projects when the mine is idle, appro- priate hourly charges must be made, or the equipment costs for coal will be higher than estimated. 3-1 4.03.0 UNDERGROUND MINE 4.03.1 INTRODUCTION This report has been developed to provide a reasonable mine layout and associated cost estimate for delivering coal to a small generating station contemplated at Wainwright, Alaska. The annual production requirement of 10,000 tons per year is quite small so that a deposit capable of supporting the generating unit over a 20-year life would not be extensive. Several coal deposits are known near Wainwright and have been reported on by the U. S. Bureau of Mines and others over the past few decades. Intermittent mining by the natives has been conducted several miles south of Wainwright along the banks of the Kuk River, and the Alaska Native Service at one time operated a mine on the Meade River some 70 airline miles from Wainwright. These sites, while workable, present a problem in transportation. A modest drilling program conducted during the 1981 field season disclosed the presence of a small coal deposit on the immediate out- skirts of the village of Wainwright (Area A-B on location map, figure 3-2, Volume 2.) The coal is quite shallow, appears to maintain a reasonable thickness, and is sufficiently continuous to provide at least a 20-year fuel supply. Because of these factors and the obvious lack of men, material, and coal transportation problems, this site was selected for analysis. 4.03.2 SUMMARY The Wainwright mine is sized to produce 10,000 tons per year by the underground room and pillar method. It is planned that it will be active only half time during the eight winter months so considerable excess capacity exists for possible future expansion. A simplified approach was used in laying out the mine and in select- ing equipment. This, together with the excess capacity mentioned above, should ensure reliable coal production. 3-2 The 20-year mine life reserve block encompasses an area of just 50 acres. Pillar sizes are believed more than ample to support the over- lying cover (particularly if the mine remains cold) and they will be left intact to avoid complicating the mining process. Resource recovery under these conditions approximates 35 percent. Actual construction time for the mine can be in the final months of the year preceding coal deliveries as shown on Figure 4.3.4. In this manner full use can be made not only of the short shipping season but also of the subsequent frozen ground conditions when the incline entry and shaft need to be excavated. It is presumed that the contractor will use local labor to the fullest extent possible so that they will be adequately trained to eventually run the mine. Maximum contractor employment will be 22, whereas the mine staff will total 14 people, comprised of 11 hourly personnel and 3 salaried staff members. Total initial capital requirements to make the mine operational will approach $2,977,000. Given some unique financing arrangements, those capital and operating costs attributable only to mining are calculated to be $72.72 per ton. 4.03.3 RESERVE ANALYSIS Basic data on the coal seam indicate that it lies approximately 120 feet below the ground surface, has a very gentle dip to the south- southeast, and carries at least a 6.5-foot thickness over a consider- able area. It should be noted that this information is derived on the basis of three or four drill holes, the closest of which are over 2,600 feet apart, and that prior to any detailed study or decision some additional subsurface information should be collected. Underground mining is the preferred choice in this situation. Some basic assumptions which have been made in order to define a mining block and determine a reserve requirement include the following: 1. Standard underground room and pillar mining would be employed. 323 2. No pillar recovery has been planned initially, but pillar recovery can be added after mining skills are developed at Wainwright. 3. Entries would be 18 feet wide on 80-foot centers; this will leave pillars 62 feet square which should be ample for support given the shallow cover depth. 4. A three-entry system will be considered for both the mains and panels in order to satisfy current federal requirements. 5. Mining will be done to the full seam height of 6.5 feet. 6. A barrier pillar will be left between panels so that sealing and complete abandonment can be effected upon completion of mining in any given panel. This obviates the need for sweeping old workings with a split of air during the remaining mine life. Table 4.3.1 shows the calculation of reserve recovery under these assumptions to be 46 percent in the main entries and 34 percent in the panels. Based on these figures, further calculations suggest that eight panels of approximately 1,000 feet in length will be required (in addition to the production from main entry development) to supply the proposed generating unit. The overall block of ground disturbed at the end of 20 years' operation will measure roughly 1,138 feet x 1,938 feet. Slightly over 200,000 tons of coal can be produced from this block at an overall recovery of nearly 35 percent. 4.03.4 MINE LAYOUT AND PLANNING Access to the coal seam logically would be via an inclined entry. The shallow cover depth will allow a relatively gentle grade without excessive length, and an inclined entry provides efficiency in men, material, and coal transport. As an emergency escapeway, however, a shaft will also be provided; this can double as an exhaust ventilation airway. Figure 4.3.1, at the end of this section, is a conceptual mine lay- out illustrating the relationship of the main and panel entries, the main roadway, and the ventilation airways; in keeping with the Mine Safety 3-4 and Health Administration (MSHA) requirements, the three-entry system will allow one fresh air intake, ome neutral airway, and a separate exhaust path. The panels are positioned solely on one side of the main entries for simplicity and to meet MSHA regulations regarding sealed panels - i.e., the seals should be swept by return air or else they require daily inspections. The proposed layout can meet these require- ments and still avoid the need for expensive ventilation overcasts. The .coal seam and surrounding sediments lie within the permafrost zone, and the frozen condition will be maintained during mining. The ambient temperature underground is estimated to be 20 to 22 degrees Fahrenheit and a long intake entryway is preferred so the incoming ventilation air is afforded ample opportunity to reach a stable tem- perature. Thus the incline will serve as the intake entry. Thawing problems can be minimized if operations cease during the summer months; because of the minimal tonnage required, production can be maintained by winter operations only. Figure 4.3.2 affords a more general view of the mining block as it would appear after 20 years' production. The inclined entry will be about 788 feet long, given a 120-foot coal seam depth and a slope of 16 percent (9 degrees). This inclination was selected since it would allow construction and eventual coal transport through the entry by diesel driven equipment. The escapeway position near the incline entry provides emergency egress as early in the mine life as possible. Even at the farthest reaches of the mine, personnel will only have to travel 3,000 feet to the shaft, much less than in some conterminous United States mines. The opportunity does exist that later a second escapeway could be constructed more proximate to the current workings if desired. Maps 4.1 through 4.4 illustrate the proposed location of the mine in relation to geological and topographic characteristics at the site. The orientation is such that main entries will be driven parallel to the seam strike and all panel development will be updip. The positioning of the 3-5 incline entry considers a surface opening location part way up a topo- graphic rise to avoid as much as possible water seepage into the entrance during summer and prevailing westerly winds in the winter. Also in this position, the entry should enter the coal seam where it is 6.5 feet thick. The mine portal will be appoximately 4,500 feet from Wainwright. Figure 4.3.3 is a cross section of the incline entry and shaft together with a generalized geologic column for reference. Anticipated support requirements for each surface opening are shown depending on the type of strata penetrated and the need to maintain the integrity of the opening over a 20-year period. In this analysis it is presumed that the first 50 feet of slope entry will be a cut and cover construction approach using a metal shell covered with an insulating agent such as polyurethane foam. A 50-foot level section will be similarly constructed to provide a means of hanging doors and sealing the mine in the summer, as well as to allow the instal- lation of an intake air heater. The next 170 feet of incline passes through near surface, sandy material and is a candidate for bolt and mesh support sealed with insu- lating foam. This should protect against ground weakening caused by summer thawing or overheated intake air. Other roof bolt/mesh segments of entry support are positioned in areas where shale or coal stringers occur in the roof. In fact this may be somewhat overdesigned if the ground remains frozen and exhibits good structural integrity as a result. Once in the coal seam, roof bolting practices as dictated by MSHA will be followed. A complete metal lining is planned for the shaft, partly for ground support but mostly as a base for attaching the necessary escape ladders and platforms. The upper 25 feet of shaft would be insulated for protection against thawing. Table 4.3.2 summarizes the ground support materials required. 3-6 An overriding concern in this feasibility analysis has been to keep the layout, equipment list, and operational approach as simple as possible, recognizing both the remoteness of location and the current lack of underground mining experience at Wainwright. It is anticipated that a contractor would be retained to drive the incline entry and sink the exhaust shaft. During this period, the contractor would use local labor as much as possible and train them in mining techniques, equipment handling, and maintenance. If the same equipment could be used in driving the incline entry and then used in mining coal, any applicable training would have full transference. Air and battery powered equipment are not believed to be applic- able at Wainwright. Air powered units in a cold environment require continuously removing entrained moisture from the airstream. Battery equipment loses efficiency with decreasing temperatures and invariably fails to get recharged on schedule. Thus only electric and diesel driven equipment are considered in this study. Discussions with equipment vendors and manufacturers' representa- tives resulted in selection of the following primary equipment items as adequate for Wainwright. More detailed analysis should be performed at some later date in an effort to optimize the equipment list. Excavator: Dosco Dintheader - capable of driving the incline and mining coal; a simple, low maintenance electrically driven unit that can excavate and load the material directly into a hauler. Avoids the need for using explosives and mitigates associated training and safety problems that would be present in a “conven- tional" coal cutting, augering and blasting system. Bolter: Long-Airdox LRB-15A - capable of bolting either rock or coal, and included in this analysis as a worst case situation. Dosco manufactures a hydraulically operated drill which can be mounted and run off the 3-7 Dintheader. This attachable unit has the potential to save capital costs and labor charges, and should be considered in detail in any future study. Hauler: Jeffrey Ramcar - this diesel driven unit has a low profile and it can fit under the discharge boom of the Dintheader in a 6.5-foot opening. It provides good visibility for the operator, and with four-wheel drive can haul 14 tons of coal up the incline to the dis- charge point. Exhaust fan: A standard off-the-shelf unit rated at a nominal 40,000 CFM capacity but has a range of 20,000 to 60,000 CFM depending on blade setting. Air Heater: Two units were selected so that large variances between outside temperature and air volumes can be taken into account. Each unit will require 305 kW and should be able to heat 20,000 CFM from -40 degress Fahrenheit to 20. degrees Fahrenheit. It is expected that the Dintheader and the bolter can be operated without the use of water sprays. A variance may be required from MSHA for this. However, the Dintheader can load coal at the rate of roughly 4 tons per minute so that only 3.5 minutes of operation will be needed to fill the hauler. Transport cycle time to the generating station at Wainwright is estimated to be nearly 29 minutes, allowing ample time for clearing any dust generated during the cutting cycle (see Table 4.3.3 for general assumptions and calculations). Permafrost conditions can be a positive factor facilitating the conduct of mining operations. Frozen ground is characterized by quite high mechanical strength, which increases the bearing capacity of pillars and the stability of the mine roof. It may be feasible to mine coal at 3-8 Wainwright with no roof bolting or only spot bolting; for conservatism though, a full bolting pattern is assumed. Permanently frozen ground is essentially impervious to gas flow so problems attributable to methane are expected to be minimal. Provided the mine is kept in its frozen state, the only potential source of water underground will be from surface melt at the portal and shaft openings. Proper construction and sealing during the summer months should avoid this situation. If an MSHA variance regarding water sprays is not attainable, it may be possible to allay coal dust with a weak antifreeze/water solution. The planned upslope panel development will be beneficial in that drainage will occur away from the face. Any spray mixture can then be collected in a sump positioned in the lowermost (fresh air) main entry for pumping and disposal at the surface. Another operational procedure which may possibly be modified because of the cold mine temperature is rockdusting. A federal regulation requires all underground mines to coat exposed coal surfaces with pul- verized limestone. Thus if an explosion occurs at the mine face, the ensuing air wave will not propagate the blast through concentrations of flammable coal dust being shaken from the pillars and ignited. However at Wainwright, it is conceivable that any residual coal dust on the pillars, roof, and walls could simply be frozen into place by the judicious application of a clear water mist. In this analysis the standard rock dusting process has been assumed pending further study. Figure 4.3.4 presents a preliminary estimate of the development schedule for the coal mine at Wainwright. It presupposes that all regulatory requirements for state and federal agencies have been satis- fied, detailed planning has been accomplished, and the construction contractor has been selected. The short shipping season in midsummer must be used, and any dirt work would be performed after the surface soil has refrozen. Table 4.3.4 provides the supporting estimates of time duration and contractor crew size for each construction activity. It appears that the Wainwright mine could be ready for production by February 1 of the year following initial construction. 3-9 4.03.5 PRELIMINARY MINE COST ESTIMATE Based on the foregoing considerations, a capital expenditure sched- ule, Table 4.3.5, has been prepared to identify expected investment in the mine. (All costs in this analysis are derived as though the mine was located in the conterminous United States. Appropriate multipliers for North Slope conditions will be applied at the end of this section.) Because of the limited planned use for most of the equipment, the oper- ating lives should be greater than normal and are so reflected in the schedule... Proximity to the village of Wainwright and to the generating station has reduced the need for certain equipment items (pickups, etc.) that would normally be included in a capital schedule. As discussed in the footnotes to Table 4.3.5, there is a potential for perhaps $200,000 in savings through select equipment purchases. No contingencies have been included in capital estimating. Initial capital requirements are $1,842,000 for depreciable items ($184 per ton of annual capacity) and slightly over $107,000 for working capital. Table 4.3.6 presents manpower schedule and costing data. As noted previously, production can be attained by working 80 days per year and annual labor costs have been derived on this basis. The fringe benefits for labor at 20 percent of direct payroll may seem low, but with 285 free days per year there seems to be little reason to schedule holiday work or make provisions for vacations. Labor costs are estimated at $12.92 per ton. Material and supply costs are detailed on Table 4.3.7; again these are based largely on the amount of time that equipment will be working. Roof bolt and rock dust usage assumes that variances from standard mining practice are not allowed; power costs are attributable largely to the heaters warming intake ventilation air. Material and supply costs are estimated to be $10.70 per ton. Table 4.3.8 identifies the major costs that will likely be imposed by outside agencies. It is recognized that, because of the owner- ship and operation of the Wainwright mine by native Americans, certain 3-10 assessed charges may not be imposed. However all federal charges are presumed in effect in this analysis for conservatism. Under these conditions assessments total $0.65 per ton plus 11 percent of mine realization price. Table 4.3.9 shows the determination of working capital requirements (included in the capital expenditure schedule) based on 90 days' cash expenditures. These will approximate $107,000. Also on Table 4.3.9 is the depreciation charge analysis; these charges total $10.60 per ton on all invested capital. It is understood that half the capital may be provided as a grant, in which case only half the calculated depreciation should be included as a mining cost. The estimate of financial charges is given in Table 4.3.10. Provi- sion is made for the 50 percent grant, and interest charges at 8 percent for 20 years on the remaining half of the initial depreciable capital. Working capital needs are financed at 8 percent in this analysis as well. Total financing costs are thus $5.64 per ton. The summary of mining costs for the Wainwright project, assuming a conterminous United States mine location, is given below. At this point it must be noted that a return on invested capital has not been included in the schedule; under this assumption the transfer price from mine to generating station would be just sufficient to cover all identifiable mine costs. 3-11 CONTERMINOUS U.S. MINE LOCATION Item Cost, $/ton Labor 12.92 Material & Supplies 10.70 Assessments 5.00 Depreciation 5.30 Financing 5.64 Total Cost ; 39.56 A straightforward factoring approach is used to convert the above estimated mine costs to a North Slope situation. The best approximation at this time indicates that a 150 percent factor be applied to capital cost items (and those unit costs related to capital investment) whereas operating costs should be doubled. Using this factoring approach, the following mining costs might realistically be expected ‘at Wainwright: WAINWRIGHT, ALASKA MINE LOCATION Item Cost ,$/ton Labor 25.84 Material & Supplies 21.40 Assessment s* 8.65 Depreciation 7.95 Financing** 8.88 Total Cost 72.72 * $0.65 of this amount is not subject to factoring because of location. *k Depreciable capital financing component increases by 150 percent; working capital component increases by 200 percent. Total invested capital to get the Wainwright mine in operation would approach $2,763,000 for depreciable assets and $214,000 for working capital, or $2,977,000 in total. ‘DIRECTION OF PANEL ADVANCE 960’ LENGTH LEGEND — CURTAIN == STOPPING = SEAL “=p= DOOR _——> INTAKE AIR —~?? EXHAUST AIR ---- COAL TRANSPORT PANEL BARRIER PILLAR EXHAUST SHAFT AND ESCAPE MANWAY. x DIRECTION OF HEADING ADVANCE —— 1938" LENGTH . ARCTIC SLOPE TECHNICAL SERVICES, INC. PRELIMINARY MINE LAYOUT WAINWRIGHT, ALASKA PREPARED BY! DE.K JOB NO. 81-001 - ORAWN BY: RD.C. SCALE # 1s 100° CHECKED BY® DATE t 9-24-81 EXHAUST SHAFT AND ESCAPEWAY- ENCLOSED SURFACE ROADWAY Je-—Incune ENTRY ARCTIC SLOPE TECHNICAL SERVICES, INC. PRELIMINARY MINE CONFIGURATION NOTE: AT 10,000 tpy, A 20 YEAR MINE WAINWRIGHT, ALASKA WOULD REQUIRE APPROXIMATELY 51 ACRES. PREPARED BY * D.E.K. JOB NO, 81-00! DRAWN BY: RD.C. SCALE ! "= 400° CHECKED BY: DATE ! 9-24-81 Fimwe aan EXHAUST SHAFT, 8' DIAM. 40 SEA LEVEL INCLINE ENTRY Tx 17' je— 100'—»e——— 170 TTI MNTTIETITT 170' ————+}e— 90> 70 CUT & COVER ROOF BOLT, MESH & _ ROOF) BOLT NO SUPPORT OR LINING ROOF BOLT NO SUPPORT OR LINING ROOF BOLTS CONSTRUCTION INSULATED FOAM & MESH REQUIRED & MESH REQUIRED PER MSHA WITH INSULATED FOAM ARCTIC SLOPE TECHNICAL SERVICES, INC. ANTICIPATED SUPPORT REQUIREMENTS WAINWRIGHT, ALASKA PREPARED BY: QE.K. JOB NO, 8I- 00! DRAWN BY: P.D.C. SCALE ! I"s 100° CHECKED BY: OATE : 10-8-81 ACTIVITY ] JUNE JULY AUG. FINAL ENGINEERING & PROCUREMENT SHIPPING AND LIGHTERING CONTRACTOR ORGANIZATION ON SITE INCLINE ENTRY CuT & COVER CONSTRUCTION INSTALL ELECTRICALS ORIVE INCLINE SURFACE FACILITIES ROAD BUILDINGS SHAFT ENTRY wi N ty v4 © B 2 < E < = SINK SHAFT ! INSTALL LINER SET EXHAUST FAN ARCTIC SLOPE TECHNICAL SERVICES, INC. MINE DEVELOPMENT SCHEDULE *™ * " ASSUMES ALL REQUISITE PLANS HAVE BEEN APPROVED | BY VARIOUS STATE ANDO FEDERAL REGULATORY AGENCIES i nn ANO ALL PERMITS HAVE BEEN OBTAINED. Ren A CAE K. Nekiioe aceon DRAWN BY: P.D.C. SCALE * NONE CHECKED BY! DATE: 10-9-8! ! cimine ARzA 3-16 TABLE 4.3.1 UNDERGROUND MINE Coal Recovery Calculations MAINS: Recovery per 80 feet of advance = 3 x 80 ft. x 18 ft. + 2 x 62 ft. x 18 ft. = 6,552 sq. ft. Total area per 80 feet of advance = 80 ft. x 178 ft. = 14,240 sq. ft. 6,552 Ta.240 = 46% Recovery = PANELS: Recovery per 80 feet of advance = 3 x 80 ft. x 18 ft. + 2 x 62 ft. x 18 ft. = 6,552 sq. ft. Total area per 80 feet of advance = 80 ft. x (178 ft. + 62 ft.) = 19,200 sq. ft. Recovery = fae = 34% > Note: Pillar recovery on retreat is not contemplated at this property, but is possible, especially with ice backfilling. It may—also be possible to reduce pillar size once the mine 2 is in operation and ground conditions can be observed. Mine Dimension Calculations Panel length: 80 ft. x 12 = 960 ft. Panel width: (3 x 18 ft.) + (2 x 62 ft.) + (62 ft. barrier pillar) = 240 ft. Panel area: 960 ft. x 240 ft. = 230,400 sq. ft. Recovery at 34%: 230,400 sq. ft. x 34% x 6.5 ft. height x 80 pcf + 2,000 1b./ton = 20,367 tons of recoverable coal per panel 3-17 TABLE 4.3.1 (Continued) Length of mains per panel = 240 ft. Width of mains per panel = 178 ft. Area of mains per panel = 240 ft. x 178 ft. = 42,720 sq. ft. Recovery at 46%: 42,720 sq. ft. x 46% x 6.5 ft. height x 80 pcf + 2,000 1b./ton = 5,109 tons of recoverable coal in mains per panel Total recoverable coal per panel: 20,367 tons + 5,109 tons = 25,476 tons Production years per panel: 25,476 tons _ 0,000 tpy 2.55 years Mine size: Production for 20 years = ses = 8 panels Mine size = (960 ft. + 178 ft.) x (1,920 ft. - 62 ft. + 80 ft.) = 1,138 ft. x 1,938 ft. plus incline = approximately 51 acres Incline at 16% and 126 ft. deep = 788 ft. (to bottom of seam) 3-18 TABLE 4.3.2 UNDERGROUND MINE Ground Support Material and Supply Calculation Incline Entry: 7 ft. high x 17 ft. wide Area = 119 sq. ft. Wall and Roof Perimeter = 31 ft. Metal Lining: 100 ft. long x 31 ft = 3,100 sq. ft. Foam Insulation: 270 ft. long x 31 ft. x 1/2 ft. thick = 4,200 eu. ft. Roof Bolts: (4-ft. bolts on 4-ft. centers) = 360 bolts Wire Mesh: 17 ft. width x 360 ft. + 10% overlap = 6,800 sq. ft. Shaft: 8 foot diameter Area = 50 sq. ft. Perimeter = 25 ft. Metal Lining: 120 ft. long x 25 ft. perimeter = 3,000 sq. ft. Foam Insulation: 25 ft. of depth x 25 ft. perimeter x 0.5 ft. thick = 315 cu. ft. Main Entryways: 6.5 ft. high x 18 ft. wide Area = 117 sq. ft. Lined Perimeter = 30 ft. Roof Bolts: (4-ft. bolts on 4-ft. centers = 1 bolt/ft. of drift length) Annual feet of main entry = 10,000 tpy x 2,000 1bs./ ton + 80 pef + 177 sq. ft. of advance = 2,140 ft. of drift. Bolt usage = 2,140 per year at 10,000 tpy. 319 TABLE 4.3.3 UNDERGROUND MINE General Assumptions and Calculations Basic Data: Cover depth: 120 ft.+ Coal thickness: 6.7-7.0 ft. Haul Distance: 4,500 ft. Entry slope: 16% Slope dimensions: 7 ft. x 17 ft. Production rate: 10,000 tons/year Production period: October through May Density of Coal: 80 1b./ft.2 in place 55 1b./ft. broken Shaft dimension: 8 ft. diameter Calculations: Monthly production rate: 10,000/8 = 1,250 tons/month Daily production rate (on a 10 day/month basis): 1,250/10 = 125 tons/day Heading width: 18 ft. Total tonnage/ft of advance: 18 x 6.5 x 1 x 80 + 2,000 = 4.68 tons Daily advance required: 125 + 4.68 = 26.7 feet Length of decline entry: 126 + .16 = 788 ft. (to bottom of seam) Transportation cycle time: (coal haulage) Initial mining at base of decline Ramp @ 2.5 mph x 750 ft. = Outside @ 6.0 mph x 4,500 ft. = min. min. min. one way travel - ) CO] Ww ° . Wim olu & 2 min. round trip travel Loading time 3.5 min. Dumping time 1.0 min. 26.3 min. Average Mining in early years Add 1,500 ft. internal mine haulage @ 5 mph = 3.4 min. one way x 2 6.8 min. round trip Total average cycle = 33.1 min. Assume 390 minutes or 6.5 working hours/day = 11 cycles/day Transporter size required: 11.4 tons Use 14 ton Ramcar 3-20 TABLE 4.3.3 (Continued) Ventilation requirements Excavator: 3,000 CFM minimum air requirement at the face for this electric unit Bolter: 3,000 CFM required, similar to the excavator 6,000 CFM; however MSHA regulations stipulate at least 9,000 CFM delivered to the intake end of a pillar line 9,000 CFM Hauler: 5,000 CFM required for the diesel engine 14,000 CFM minimum required air quantity +6 ,000 CFM to counteract lack of sprays 20,000 CFM x 2 to consider leakage, losses, etc. 40,000 CFM Total Air velocity check: V = Q/A Intake entry area: 6.5 x 18 = 117 et.? v = 40,000 + 117 = 341 ft./min. = 3.9 mph Exhaust shaft area = (4)? = 50 £t.2 v = 40,000 + 50 = 800 ft./min. = 9.0 mph Personnel will be exposed to the 3.9 mph air stream which should present no undue chilling even at a 20°F ambient temperature Air heating calculations Mean January temperature -20°F —— Average minimum January—temperature—— 5 OSB ica Ambient mine air temperature 20°F Assume a 10° temperature change will consume 2.2 Btu/1b. of dry air for temperatures below 32°F (100 gm H,O per 1b. 2 of dry air basis) Assume specific volue of dry air = 13.5 £t.?/1b. 60 x 40,000 Weight flow rate 35 = 177,777 1b. of dry air/hr. Heat requirements at mean temperature difference = 40/10 x 2.2 x 177,777 = 1,564,000 Btu/hr. Heat requirements at maximum temperature difference = 70/10 x 2.2 x 177,777 = 2,738,000 Btu/hr. Since 1 kW hr. = 3412 Btu, the power needed for heating the intake ventilation air will be in the range of 460-800 kW Building Requirements: Shop/Warehouse: Admin./Changehouse: Diesel Storage: 3-21 TABLE 4.3.3 (Continued) 3 bays for overnight parking of diesel equipment, and normal maintenance and storage 30 ft. x 90 ft. = 2,700 ft? 3 offices, secretarial space, and 10-man shower facilities 2 30 ft. x 50 ft. = 1,500 ft. including outside dock 2 30 ft. x 20 ft. = 600 ft. 4,800 £t.* 3-22 TABLE 4.3.4 UNDERGROUND MINE Construction Time and Crew Size Calculation Decline Entry: Organize crew; rip and doze 50 linear feet of decline, erect 100 feet of liner shell, apply foam insulation. Crew size: 5 Duration: 2 weeks Install mine transformers, extend electrical facilities, install mine ventilation heaters, install transformer for exhaust fan. Crew size: 4 Duration: 3 weeks Drive 700 feet of 16 percent decline, install appropriate lining and ground support. Crew size: 7 Duration: 8 weeks Total Decline: 78 man-weeks Shaft Entry: Sink 8-foot diameter shaft from the surface to approximately 100- foot depth using two drills, hand-mucking,—erane-hoist. es Crew size: 5 Duration: 4 weeks Install shaft liner, ladders, platforms, and apply foam insulation. Construct sun shade. Crew size: 5 Duration: 2 weeks Construct fan base, install fan, hood, ducting, and blowout doors. Crew size: 5 Duration: 2 weeks Total Shaft: 40 man-weeks 3-23 TABLE 4.3.4 (Continued) Surface Facilities: Construct road from Wainwright to the mine site. Construct foun- dations and erect 4800 square feet of facilities, including electri- cals, plumbing, and equipment. (Road must be constructed before thaw season.) Crew size: 10 ' Duration: 8 weeks Total Surface: 80 man-weeks (less if road built by others) Summary: Maximum contract personnel on site: 22 Total contractor requirements (including 8 man-weeks receiving shipments): 206 man-weeks Total contract labor costs estimated at $350/man-day. (This average charge includes ownership and operating costs for associated light equipment.) 206 man-weeks x 5 days per week x $350 per day = $360,500* * Lower 48 costs in 1981 $ 17A, #1 18A, #1 TABLE 4.3.5 = UNDERGROUND MINE 3-24 Capital Costs - Lower 48 3rd Quarter 1981 $ Life In No. of Unit Total ITEM _ Years _ Units Cost $ Cost $ Year -2 Year -1 Year 1 Year 2 Year 3 Yeer 4 Year 5S Year 6 Year 7 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 TOTAL UNDERGROUND MINING EQUIPMENT Dosco Dintheader 20 1 400 ,000* 400,000 400 ,000 200 ,000*** 600 ,000 Long Airdox LRB 15A Bolter 20 1 44 ,000** 44,000 44,000 22 ,000*#* 66,000 Jeffrey 4114 Ramcar 20 1 185,000 185,000 185,000 93 ,000*** 276,000 SUPPORT EQUIPMENT UNDERGROUND Joy 4226 Exhaust Fan 20 1 32,000 32,000 32,000 ietnen Trane Air Heaters 20 2 23,000 46,000 46,000 7 2000 MSA miscellaneous items: mine 5 lot 20,000 20,000 20,000 20,000 20,000 20,000 80,000 lamps, self rescuers, fire extinguishers, methanometers, roof jacks, rock duster 18,000 Joy 256T Auxiliary Fan 10 1 9,000 9,000 9,000 9,000 7 SUPPORT EQUIPMENT SURFACE **** eA Caterpillar D-7 10 1 209 ,000 209 ,000 209,000 ‘ — 202,000 TOTAL EQUIPMENT 945,000 945,000 20,000 344,000 20,000 1,329,000 BUILDINGS & SURFACE FACILITIES 7 2 oe Mine Shop/Warehouse, 2,700 ft, 20 1 45/£t.5 122,000 122,000 122,0 Admin./Changehouse, 1,500 ft, 20 1 40/£t.9 60,000 60 ,000 ts ong Diesel Storage/Dock, 600 ft. 20 1 25/ft. 15,000 15,000 oe oc Road, 4,500 ft. 20 1 20/ft. 90,000 90 ,000 2000 Powerline 4,500 ft. Transformer 20 1 10/ft. 45,000 45,000 45,000 PRE-PRODUCTION DEVELOPMENT > Incline Entry, 750 ft. 20 1 300/ft. 225,000 225,000 eee Shaft, 100 ft. 20 1 1400/f£e. 140,000 140,000 rho;000 Engineering & Permitting 20 lot 200,000 200,000 150,000 50,000 —200 000 TOTAL FACILITIES & DEVELOPMENT 897,000 150,000 747,000 —— a —— 897,000 TOTAL CAPITAL EXPENDITURES 1,842,000 150,000 1,692,000 20,000 344 ,000 20,000 2,226,000 WORKING CAPITAL*#*** 107,200 2207 ,200 TOTAL CAPITAL INVESTMENT 150,000 1,692,000 107,200 20,000 344,000 20,000 2,333,200 less than $200,000. ae ehhh such as pickups, are probably not mandatory at Wainwright. xekee Working capital will be returned in year 20. This is the cost of a new unit; however, Kaiser's Sunnyside, Utah mine has an unused Dintheader which probably could be acquire! for A worst case situation is implied by the purchase of a separate bolter; Dosco can adapt a small drill to operate from the Dinth:ader hydraulic system, which should be sufficient for the planned operation at Wainwright. A major overhaul, costing half the original purchase price, is suggested for the primary pieces of mining equipment at this time. A front-end loader that would work from the stockpile is presumed a part of the plant capital; miscellaneous items normally inc.uded, 3-25 TABLE 4.3.5A UNDERGROUND MINE ESTIMATED WAINWRIGHT COSTS* 3rd QUARTER 1981 $ YEAR AMOUNT -2 225 ,000 -1 2,538,000 1 (first production) 214,400 5 30,000 10 516 ,000 15 30,000 TOTAL 3,553,400 * Capital costs estimated at lower 48 costs (Table 4.3.5) times 1.5. Working capital estimated at lower 48 costs times 2.0. 3-26 TABLE 4.3.6 UNDERGROUND MINE Manpower Schedule and Annual Costs Lower 48 Costs, 3rd Quarter 1981 $ HOURLY LABOR * Based on 1/3 time, or 80 operating days/year Daily Total Annual Classification Wage Rate, $ Personnel Labor Costs, $* Miner Operator 95 1 7,600 Miner Helper : 91 7,300 Bolter Operator 95 1 7,600 Transport Operator 88 1 7,000 Utility Man 85 2 13,600 Ventilation 85 1 6,800 Maintenance ; 95 2 15,200 General 85 —2— 13,600 11 78,700 SALARIED STAFF Mine Foreman 1 14,000 Warehouse & Supply 1 9,000 ~~ Accounting & Payroll ea on ee 6,000 _— 3 29,000 TOTAL MINE DIRECT LABOR 14 107 ,700 _ FRINGE BENEFITS @ 20% 21,500 TOTAL MINE LABOR COSTS 129,200 Unit Labor Costs 12.92/ton 3-27 TABLE 4.3.7 UNDERGROUND MINE Material & Supply Costs Lower 48 Costs, 3rd Quarter 1981 $ EQUIPMENT ; Annual Item Usage* Unit Cost** Annual Cost, $ Dosco Dintheader 320 hr. 44.00/hr. 14,100 Long Airdox Bolter 320 hr. 4.00/hr. 1,300 Jeffry Ramcar 640 hr. 16.70/hr. 10,700 Joy Fans 640 hr. 0.30/hr. 200 Trane Heater 640 hr. 0.60/hr. 400 Caterpillar Dozer 480 hr. 25.10/hr. 12,000 * Estimated equipment running time *k Repairs and Replacements BUILDINGS & SURFACE FACILITIES Mine Shop/Warehouse 5% Initial cost 6,100 Admin. /Changehouse 5% Initial cost 3,000 Diesel Storage/Dock 5% Initial cost 800 Road 10% Initial cost 9,000 Powerline 5% Initial cost 2,200 MISCELLANEOUS SUPPLIES Roof Bolts 2,140 3.30 ea. 7,100 Rock Dust 50 tons 30.00/ton 1,500 Concrete Block 1,000 0.60 ea. 600 Fuel 8,000 gal. 1.25/gal. 10,000 Power 700,000 kW-hr. 0.04/kW-hr. 28,000 * TOTAL MINE MATERIAL & SUPPLY COSTS 107 ,000 Unit Material & Supply Costs 10.70/ton * The unit cost of 0.04 per kwh is far too low. However, since heating of the ventilation air will not be done by electricity, but by hot fluid from the Central District Heating System, the cost will not materially exceed that shown. 3-28 TABLE 4.3.8 UNDERGROUND MINE Estimate of Assessments 3rd Quarter 1981 $ l. Black Lung Tax: 2% of mine realization price, not to exceed $0 .50/ton. At Wainwright the maximum assessment will be used. 2. Reclamation Tax: $0.15/ton for underground coal. 3. Royalties: Federally owned, deep mined coal carries an 8% royalty based on mine realization (selling) price. At Wainwright, because of the captive nature of the proposed mine/generating station, the transfer price may be just the actual cost/ton without consideration of a normal return on investment. 4. Severance Tax: The state of Alaska does not currently impose a severance tax on coal although considerable discussion is centering on a proposed levy amounting to 3% of mine realization price. The state does have a mining license tax that is imposed on a sliding scale from 2-7.5% of net profits, the maximum rate being applied on net profits in excess of $100,000. Enactment of a severance tax would negate the mining license levy. In this analysis the 3% severance tax will be used. 5. North Slope Borough Tax: This is a tax applied to property improve- ments with the beneficiaries being the natives. Since this mine will be operated by the natives for their own benefit, there seems to be no point in assessing this tax. Total Assessments: $0.65/ton* plus 11% of mine realization price * No adjustment will be required for North Slope conditions. 3-29 TABLE 4.3.9 UNDERGROUND MINE Working Capital Requirements Lower 48 Costs, 3rd Quarter 1981 $ (90 days out-of-pocket expenses, or 3750 tons of production) Supervisory & Professional Staff $ 13,000 Operating & Maintenance Personnel 35,400 Material & Supply Costs 40,100 Assessments 18,700 $107,200 Depreciation Charges (Straight Line Basis) Depreciation Item Total Cost, $ Cost/Ton 5-year life: Miscellaneous 20,000 $ 0.40 10-year life: Auxiliary fan, dozer 218 ,000 2.18 20-year life: Mining equipment, surface facilities pre-production development 1,604 ,000 8.02 $10.60 The $10.60/ton charge represents straight line depreciation on total wasting investment. If the project obtains 50% of its capital needs in the form of a grant, only half, or $5.30/ton, should be included as a cost of mining. 3-30 TABLE 4.3.10 UNDERGROUND MINE Estimate of Financial Charges Lower 48 Costs, 3rd Quarter 1981 $ Assumptions: ; In this study it is assumed that 50% of the capital needs for the project will be obtainable as ‘a grant, and that the remaining 50% will require repayment, together with interest charged at 8%. Calculations: The function of depreciation in a business venture is a recognition of the wasting nature of assets, and when included in the sales price of a product, allows the owner to collect over time sufficient money to replace the asset when required. In this sense it is a repayment of capital without interest. Since depreciation is included as a cost item, only the associated interest charges need be calculated. The approach here has been to determine an annual annuity payment to retire the principal and pay interest, multiply this figure by 20 to cover the 20-year life of the project, then subtract the beginning capital. The remaining figure is pure interest which can then be allo- cated to each ton produced. As the working capital will be returned at the project's close, just straight annual interest charges need be determined for this portion of investment. Total Depreciable Capital: $1,842,000 Amount subject to financing 921,000 Annuity to repay over 20 years at 8% 93 ,800 Total payments over 20 years 1,876,000 Less Principal 921,000 Total Interest on Depreciable Capital $ 955,000 Total tonnage Produced 200,000 tons Interest charge/ton $4.78 3-30 TABLE 4.3.10 (Continued) Total Working Capital $107 ,200 Annual interest at 8% 8,600 Annual tonnage produced 10,000 tons Interest charges/ton $0.86 Total Financing Charges $5.64/ton 4-1 4.04.0 REFERENCES Abel, John F., Jr.; 1960. Permafrost Tunnel, Camp TUTO, Greenland. U.S. Army Snow, Ice and Permafrost Research Establishment, U.S. Army Corps of Engineers, Technical Report 73, 19 pp. Bottge, Robert G., (1977). Coal as Fuel for Barrow, Alaska: A Preli- minary Study of Mining Costs. U.S.B.M. Open File Report OFR 88-77, 71 pp. Cassidy, S.M., Ed., 1973. Elements of Practical Coal Mining. A.I.M.E., New York, 614 pp. Cedarstrom, C. J., et al, 1953. Occurrence and Development of Ground- water in Permafrost Regions. U.S.G.S. Circular 275, 49 pp. Chaban, P.D., 1973. Effect of Geocryological Conditions on the Effi- ciency of Mining Operations in the Northeastern USSR. U.S. Army CRREL Draft Translation 438, pp. 147-154. Church, H.K., 1981. Excavation Handbook. McGraw-Hill Book Company, New York, pp. 8-1/8-36. —..-_Diek, RAs, 1970. Effects of Type of Cut, Delay, and Explosives on Underground Blasting in Frozen Gravel. U.S.B.M. R.I. 7356, 17 pp. Dorman, K.R., & Gooch, A.E., 1970. Spray-Applied Polyurethane Foam to Insulate Heated Rooms Excavated in Permafrost. U.S.B.M. R.I. 7392, 43 pp. Ferrians, Oscar J., et al., 1969. Permafrost and Related Engineering Problems in Alaska. U.S.G.S. Professional Paper 678, 37 pp. Hopkins, D.M. et al., 1955. Permafrost and Groundwater in Alaska. U.S.G.S., Professional Paper 264-F, pp. 113-146. 4-2 Kaiser Engineers, Inc., 1977. Technical and Economic Feasibility Surface Mining Coal Deposits North Slope of Alaska, for U.S.. Bureau of Mines. Komarkova, V. and Webber, P.J., 1980. Vegetation Succession and Re- covery of Old Oil Wells on the Alaskan North Slope in Proceedings: High Altitude Revegetation Workshop No. 4, Institute of Arctic and Alpine Research. Lachenbruch, Arthur H., 1970. Some Estimates of the Thermal Effects of a Heated Pipeline in Permafrost. U.S.G.S. Circular 632, 23 pp. » 1957. Three Dimensional Heat Conduction in Permafrost Beneath Heated Buildings. U.S.G.S. Bull. 1052-B, pp. 51-69. Linell, Kenneth, A. and Lobacz, Edward F., 1978. Some Experiences with Tunnel Entrances in Permafrost in Third International Conference on Permafrost, Proceedings, Vol. 1, Cold Regions Research and Engineering Laboratory, pp. 813-819. Lynch, D.F., et al., 1978. Constraints on the Development of Coal Mining in Arctic Alaska Based on Review of Eurasian Arctic Practices. U.S.B.M. OFR 41-78, 230 pp. Martin G. C. and Callahan, J.E., 1978. Preliminary Report on the Coal Resources of the National Petroleum Reserve in Alaska. U.S.G.S. Open-File Report 78-1033. Martin, Gary C., 1980. Preliminary Results on the Coal Stratigraphy and Resources of the Nanushuk Group from a Shallow Geophysical Logging Program in the Wainwright Inlet - Peard Bay Area, Northern Alaska. U.S.G.S., Open File Report. 4-3 McCusker, T.G., and Tarkoy, P.J., November 1976. The Use of Tunnelling to Develop Arctic Oil and Gas Reserves. CIM Bulletin, pp. 111-112. Parker, A.D., 1970. Planning and Estimating Underground Construction. McGraw-Hill Book Company, New York, 300 pp. Peng, S.S., 1978. Coal Mine Ground Control. John Wiley & Sons, Inc., New York, 450 pp. Pettibone, H.C., 1973. Stability of an Underground Room in Frozen Gravel in Proceedings 2nd International Conference on Permafrost. National Academy of Sciences, Washington, D.C., pp. 699-706. Pike, A.E., 1966, Mining in Permafrost in Proceedings International Conference on Permafrost. National Academy of Sciences, Washington, D.C., Pub. 1287, pp. 512-515. Sanford, Robert S. and Pierce, Harold C., 1946. Exploration of Coal Deposits of the Point Barrow and Wainwright Areas, Northern Alaska. U.S.B.M., R.eI. 3934. Sellmann, ‘Paul V., 1967. Geology of the USA CRREL Permafrost Tunnel Fairbanks, Alaska. Cold Regions Research and Engineering Labora- tory, U.S. Army Materiel—Command, Technical Report-199.——————— Stenson, T.F., September 1978. State Taxation of Mineral Deposits and Production. U.S. Department of Agriculture, Rural Development Research Report No. 2, 53 pp. Swinzow, George K., 1970. Permafrost Tunneling by a Continous Mechanical Method. Cold Regions Research and Engineering Laboratory, U.S. Army Corps of Engineers, Technical Report 221. 4-4 » 1964. Tunneling in Permafrost, II. Cold Regions Research and Engineering Laboratory, U.S. Army Materiel Command, Technical Report 91. Weber, W.W., & Teal, S.S., 1959. A Sub-Arctic Mining Operation. Trans- actions Canadian Institute of Mining and Metallurgy, Vol. LXII, pp. 254-258. Williams, John R. 1970. Ground Water in the Permafrost Regions of Alaska, U.S.G.S., Professional Paper 696, 83 pp. Sel 4.05.0 MANUFACTURERS & SUPPLIERS Dosco Corporation Denver, Colorado (303) 321-5597 David Neil Banderet Equipment Company Denver, Colorado (303) 289-5793 John Burnell Jeffrey Mining Machinery Div. Columbus, Ohio (614)297-3123 John Smith U.S. Gypsum, Metal Products Div. Chicago, Illinois (312) 321-5860 John Szabo Martin-Trost Associates Golden, Colorado (303) 279-4255 Bill Martin The Trane Company Denver, Colorado (303) 779-0787 Lyle Breshears Wagner Equipment Company Portland, Oregon (503) 255-2863 Harold Kammerzell Long-Airdox Company Salt Lake City, Utah (801) 637-3236 Jim Diamanti Joy Manufacturing Company Denver, Colorado (303) 388-5891 Bob Smith Safe Lok Systems, Inc. Denver, Colorado (303) 761-1820 Jim Farrell Mountain States Machinery & Supply Price, Utah (801) 637-1434 Chuck Buchanan Alaska Department of Natural Resources Anchorage, Alaska (907) 276-5113 David Hedderly-Smith 1. 2. APPENDIX A Supporting Documentation “Permafrost Tunneling by a Continuous Mechanical Method” by George K. Swinzow “Tunneling in Permafrost, II” by George K. Swinzow Jes le | PERMAFROST TUNNELING hy A CONTINUOUS MECHANICAL METHOD George K. Swinzow - November 1970 | DA TASK 1T062112A13001 CORPS-OF ENGINEERS, U.S. ARMY COLD REGIONS RESEARCH AND ENGINEERING LABORATORY HANOVER, NEW HAMPSHIRE THIS COCUMENT HAS BEEN APPROVED FOR PUBLIC RELEASE AND SALE; ITS DISTRIBUTION IS UNLIMITED. <a OR RT fr ee : ‘ t ‘PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD by George K. Swinzow INTRODUCTION >urpose This research was part of an effort to investigate methods of subsurface excavation for military installations in perennially frozen ground. Special emphasis was given to studies of the yermafrost, its interaction with man’s underground activity, and the properties of the tunnels, such as deformation, natural air flow, feasible types of ventilation, and the thermal regime. For the purpose of this paper, permafrost is defined as unconsolidated soil such as alluvium, oraine, sand, silt or gravel deposits cemented by ice. As long as it is frozen it may be very similar to such rocks as conglomerate, sandstone, siltstone, etc. Usually the pore ice cement remains solid to temperatures very close to 0C, é a The capacity of permafrost to absorb high velocity shocks without excessive shattering is attractive for military purposes (research on this is presently in progress). Roofs of tunnels and , oms excavated in permafrost are easily made safe and are relatively stable under explosive shock oads, Relative ease of excavation and the fact that the internal temperature is always appreciably higher than the air temperature during the arctic and subarctic winter mean that tunnels in perma- “rost are effective weather shelters. _ Over the years man has developed three methods of frozen ground excavation: steam points, high pressure water jets, and explosives, used in hard rock tunneling. The explosives method was applied, tested and modified for use in permafrost during a special research program in Greenland (Abel, 1960: Swinzow, 1964). . Excavating a test tunnel in permafrost.and studying the continuous mechanical tunneling method in this environment were the prime objectives of this study. A further objective was eval- - wation of the subsurface opening as a shelter, storage space, and site for military activity. Fur- ther, the tunnel provided opportunities to conduct geological, paleogeographical and rheological Studies of an important type of permafrost. This report concentrates mainly on the tunneling method, the process of cutting frozen ground, and some general properties of the tunneL Mining classification of permafrost Eg Tunneling in ‘‘warm"’ unfrozen rock is a highly developed art. The engineer confronted with such a task may confidently predict costs and time, depending upon the type of strata, lithology and ground water conditions. However, relatively little is known about tunneling in permafrost. 2 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD toe orm ermces owen To establish a ‘‘first generation” basis for planning an excavating, mining or tunneling i operation in permafrost, we may regard two aspects of it: 1) properties to expect in any perma- frost regardless of composition, and 2) properties of the particular permafrost deposit to be worked, such as ice content, mechanical composition of constituent minerals, and temperature. ‘ In general the mining engineer can expect no water problem as long as tunneling proceeds in the frozen layer (not at its top or bottom). He will encounter temperatures below the melting point that Muctuate only slightly over the seasons. He miy expect the winter temperature [0 be considerably lower outside than in the tunnel. The particular deposit of permafrost may affect the excavation by having more or less ice cement, more or less coarse soils and boulders, and Jower or higher temperatures. ALD these factors affect the operation and must be known in advance. To predict difficulty and the extent of needed effort, one may begin by setting up a classi- fication framework. The proposed classification (Table !) is based on arbitrarily set boundaries of the three main parameters: temperature, ice content and mechanical composition. Table I. Mining engineer’s classification of permafrost (proposed). Temperature Ice content Size of material Cold -7 to -10C (19 to 14F) Intermediate -4 to -7c mY. (25 to 19F) < : : } | Warm u ae | -0.5 to -4C i E (31 to 25F) The arbitrary parameters are arranged in three columns in the order in which they cause in- - BE creasing difficulties. The first’ column begins with cold permafrost and ends with warm perma- : i frost. The limits are -10C, a temperature to be expected at very few sites, and -0.5C, above f which hardly any stable permafrost exists. Ice content is regarded in terms of the degree of sat- Br uration. Relatively dry permafrost may be excavated more easily than ice-saturated material, but i roof stability may decrease with decreasing amounts of ice cement. Furthermore there is the problem of maximum span. It is obvious that in dry permafrost one should allow for less span than 4 i ina fully saturated permafrost. The third column reflects the composition. An abundance of boulders, especially metamorphic and igneous material, leads to difficulties of a primary nature, e.g. hard rock drilling and unfavorable powder ratios with overburden. In column 3, the upper q item in each temperature range is always the more favorable for excavation. The table shows that a cold permafrost consisting of fine material strongly cemented by : | abundant ice is more advantageous than warm, undersaturated material consisting predominantly : \ of large boulders. The table is intended to predict technical difficulties and assist a mining : engineer in planning and selecting the excavation method for a given location. . For example, a ‘ meee PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 3 location in the northern archipelago of Canada with cold permafrost with intermediate to high ice content, consisting of predominantly bouldery material, requires modified hard-rock excavation methods such as those described by Swinzow (1964). Roof instability problems are insignificant and can be remedied by application of quick back-freezing slurries. Overbreak and slabbing can be handled similarly. The engineer can probably expect a somewhat higher powder ratio, but he may cross most of the timber and all of the concrete off his list. : At the other extreme is a warm permafrost with low ice content and coarse boulders. There are problems with all engineering features. The rate of advance may become low due to over- break. An unstable roof requires a large amount of timber work while man and machine are jeop- ardized by thawing in the roof. : ENVIRONMENT Location and strata The site of the Alaska Experimental Permafrost Tunnel is an abandoned gold dredging field. During mining operations the central part of Engineer Creek Valley was stripped of its overburden of perennially frozen silt and the underlying gravel was dredged for gold and dumped in small hills, ‘dry and unfrozen. The edge of the field is a steep, unstable cliff of overburden. At its foot the gravel was smoothed out and a mining camp erected. The portal was constructed in the steep cliff at the boundary of the gold field and the tunnel was driven into the perennially frozen silt (Fig. 1). The perennially frozen Fairbanks silt, first described by Mertie (1937), is supersaturated and contains large lenses, wedges and veins of ice. The deposit is stratified; streaks of sand (fine and coarse) and gravel are common throughout the tunnel. A distinct characteristic of the tunnel is its odor, derived from partially preserved organic material in the frozen silt. The pres- ence of abundant partially preserved animal and plant material indicates the possibility of syn- genetic* origin. The microscopic appearance of the silt’s fabric is that of an open packing impossible to achieve by ordinary sedimentation. Figure 2 is a polished section of a frozen sam- ple made by a technique similar to that used in metallurgy. The blank portions represent clean ice. Note that the packing is open in the coarser as well as in the clay-size fraction. 2 ORILL VERTICAL EXAGGERATION 2:5 2 HOLES 2 ORILL HOLES DRAINAGE CAMP SITE CISTERN AURIFEROUS GRAVELS TTENTIR BEOROCK Figure 1. Schematic geological cross section along the axis of the tunnel. ° Permafrost formed during deposition. PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD b. Section with mainly fine, clay-size particles. 5 Figure 2. Polished sections of Fairbanks silt photographed in reflected light (Ultropak method). Figure 3 shows slides of two typical ingredients of Fairbanks silt. The 0.1-mm particles (Fig. 3a) are predominantly micas, such as biotite, muscovite and phlogopite, with only a few other minerals like quartz and the feldspars. Figure 3b, an assemblage of 0.01-mm grains, contains most of the quartz and feldspars with a few other minerals. The grains smaller than 0.1 mm were essentially monomineralic and apparently very little mechanical rounding had occurred (the par- ticles were angular and unweathered). Clay-size material (not illustrated) was mostly sericite mixed with ordinary clay minerals such as montmorillonite and kaolinite. Vertical exploration drilling, as well as tunneling, disclosed inclusions of stones in amounts increasing with depth. These stony inclusions are, as a rule, of very low sphericity and vary from a fraction of an inch in diameter to cobble size (4 to 7 in.). Figure 4 is an example of an At the time the machine was excavating this area, about 74 ft from the area with large stones. : presenting a similar pattern in a plane perpendicular portal, the structure occupied the cutting face, emmmuest PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD b. 0.01-mm particle - quartz, feldspars, occasional garnets. Figure 3. Microslides of Fairbanks silt (Ulwopak illumination). 5 6 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD Figure 4. Structure of stone inclusions 74 ft from portal. Scale in center of photo: 1 in. = 1% ft (approximately). to that of the picture. The impression was of an excavated asymmetrical sorted stone polygon of the type described by Corté (1962). The gravel underlying the Fairbanks silt is a very angular, inhomogeneous material with very low sphericity. Generally its appearance is similar to the material exposed in the tunnel (Fig. 4). The Fairbanks silt stratum does not have a sharp lower boundary, but becomes gradually richer in rock fragments. It is possible that the ‘‘gravelly’’ exposures in the tunnel are results of frost action upon the auriferous gravels during the silt deposition. - The exact mode and rate of deposition of the Fairbanks silt cannot be explained satisfac- torily. Available literature suggests a variety of origins. Péwé (1955) conducted geological mapping of the area and hypothesizes that the “‘upland silts’’ as he calls them were deposited by an eolian process. He includes ‘the process of loess formation in the depositional cycle. Taber (1943) presents the stratigraphic position of the silt as a whole including its frozen , parts. The permafrost tunnel disclosed strata in the Fairbanks silt indicating discontinuous depo- sition rates with patterned ground and ice wedge formation. Figure 5 is an example of a probable former “‘daylight” surface such as is usually displayed by hummocky tundra. Such a formation would be possible only during a break in soil deposition. Numerous ice wedges, autochthonous ice masses and segregation veinlets also indicate interrupted deposition or changes in its rate (Fig. 6). Detailed study of plant remnants in the tunnel may lead to evidence of climatic changes during the deposition of Fairbanks silt. Figure 7a shows a Stratum rich in tree-root remnants; Figure 7b shows an ice wedge buried by subsequent deposition. Thermal environment Geographically the Fairbanks area is near the southern border of discontinuous permafrost. The mean annual temperature in the area is very close to -3.3C, Freezing weather is remarkably prevalent. Normally a slight excess of days with frost over thawing weather is sufficient for | Song PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD Figure 5. Patterned organic inclusion layer. Probable origin: buried tundra humps. a b. 150 ft. Ice veinlets and flat lens. Figure 6. Some types of ice appearing in the tunnel. -7 AE aan Me ecnr™s aaeks ey 128 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD : | - { De | a. Section at 60 ft. Tree roots preserved in permafrost. i | Gravelly beds visible in upper left corner. ‘| \ ! t ~ _ i a é oe ey “4 1 ft ' aie ashlar cSasebs b. Ice wedge at 124 ft. Figure 7. Some details of tunnel wall. to permafrost formation. The Fairbanks area has a ratio of freezing degree-days to thawing degree- days of approximately 1.7:1. One would expect to find continuous pemnafrost with a temperature . about the same as the yearly average. On the contrary, the permafrost of the Fairbanks area is ! , | warm (minimum temperature around -2C) and discontinuous. One reason for this might be an in- : : creased geothermal flux of which there is some evidence in the area. However, as far as could be determined, the geothermal gradient in this region has never been studied with sufficient ; [ is accuracy to explain an apparent anomaly. TS The area is relatively dry - about 30 cm of precipitation per year. The snow cover is.up to 100 cm thick. , | PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 9 Physiography The permafrost in the Fairbanks area is discontinuous. - Hills and ridges are as a rule un- frozen; southern slopes are unlikely to have permafrost while the greatest depths are in narrow valley floors. One possible explanation for this is that there are frequent winter thermal inversions in the area. Weather records from Fairbanks as wéll as from the tunnel site show that when air temperatures at higher elevations are as high as -20 to -30C, valley Moors may be at -40 to -50C. Normally the borderline between permafrost and unfrozen ground is not asimple vertical cut- off. It is either a progressive thickening of the active layer to a point where it only rarely fuses with permafrost at the time of greatest winter frost penetration, or the lower boundary of the perma- frost becomes progressively shallower until it reaches the winter depth of freezing. . Preliminary field explorations disclosed both. Moving up the valley slope approximately along the axis of the tunnel, we found, by drilling, a progressive thickening of the seasonal frost liiyer together with thinning of the perennially frozen layer until both met, which was considered to be a local border of the permafrost area. In some cases there was more than one frozen layer in only a few meters of depth. It is apparent, therefore, that the perennially frozen silt body must be in the form of a concave-convex lens in cross section with neither surface parallel to the topo- graphic profile. - , For further discussion conceming details of the tunnel site geology, geomorphology and _eryopedology, see Sellmann (1967). McCoy (1964) gives a series of gradation curves reflecting the mechanical composition of the frozen silt as well as the limits of its changes. - SELECTION OF MINING PRINCIPLE The tunnel site is 11 miles north of Fairbanks near the Steese Highway. The local perma- frost is warm (around -1C), fine grained and has a high ice content (up to 65% by volume). Pre- liminary geological site exploration disclosed possible severe difficulties for the rock drill and a low response to explosives. It was therefore caly logical to scrutinize one of the continuous mechanical methods used in the coal industry, Parameters for selection of a suitable machine were to be weight, power requirements, and degree of mobility, together with initial cost. An additional point was the search for some novel principle with an obvious technical advantage. An pxtensive survey was made among the existing continuous mechanical mining systens. - Six machines were selected for final comparison. Their fundamental properties are summarized in Table Il. On the basis of the data in Table If the Alkirk Continuous Cycle Miner (Fig. 8) was selected. Its relatively low weight constituted a major logistical advantage. Its power consumption was also advantageous, and it employed a novel principle, the so-call ‘‘pilot pull principle.” Any continuous mechanical miner must incorporate four functions: 1) locomotion (tramming) to move toward the face; -2) sufficient thrust against the face for the cutting teeth to dig into the material; 3) disintegration of the material at the face by means of continuous motion of the cutting tools; and 4) delivery of the cuttings away from the face to a place-where they may be conveyed to the surface. | 2: ahd pees: 10 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD Table 0. Selected properties of six mechanical mining systems. Approx. basic ‘Gross price ts weight System (1962)° (tons) Remarks ____ Sysen CU ma ah0v— Foundation Co. of Canada 3 75.000 60 Applied in Toronto in : soft shale and limestone. Breakdown reported. Robtmns Cont. Miner 290,000 . 35 Machine successful in * (basic) soft formations. Large > power requirements. Goodman System 150,000 52 ~ Used successfully in (Type 428) potash mining. Power : . requirement: 600 hp. Joy Mfg. System 150,000 40 Machine would need to (2BT-2) (basic) be redesigned. Requires 600 hp. > Alkirk Pull Principle 150,000 12.5 Machine applies a unique pull principle. Requires 225 hp. Kirk-Hillman | 150,000 est. No record of successful : 30 application available. Power requirements un- known. UPPER . cusP MAIN CUTTER ARMS . . CUTTER WITH HOLDERS ANO TEETH SHIELD CONVEYOR Sie ama SES PILOT CUTTERS : EXTENDED PACKERS RETRACTED —~— —_— Figure 8. The Alkirk Continuous Miner r ange ee PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD ll To accomplish the second function the Alkirk miner employs the unique twin pilot-pull prin- ciple. Two 8-in. pilot cutters drill two anchor holes into the rock face and are fastened into them ahead of the machine. After the pilot holes are drilled and the anchoring packers set, the main cutting arms are engaged and rotate in opposite directions. The machine then moves into the face by pulling against the two anchors, The machine dges not rely upon its own weight for foward thrust nor does it need hydraulic wall rams or excess traction force. The two main 7-ft-diam cutting arms rotate on centers 5.5 ft apart so that the circles they scribe on the face overlap. The two cusps left on roof and floor are removed by two arrangements: an upper rigid-axis cusp cutter and a lower cutting link-chain conveyor urmed with drag bits. The conveyor also removes the cuttings to the rear of the machine for tramming out. Below are given some technical data on the machine necessary for further discussion. More details of a functional nature are given by McCoy (1964). , Dimensions: ; Diameter of miner cutters - Th r Diameter of pilot borers 8 in. Distance between centers 5 ft 6 in. Work stroke, maximum 5 ft Cut dimensions: Vertical Tt : Horizontal 12 ft 6 in. ‘ Drive: Liquid-cooled electric motor, 200 hp, 1800 rpm, 440 v, 60 cycle, 3 phase ; explosion proof, 200% overload. 7 Main cutter drive: Worm gear type, two speed: 10-and 15-rpm pilot cutter drives. Hydraulic motor speed about 110 rpm. : Track drive: 7 Independently controlled hydraulic motor; infinitely variable speed; 0 - 30 rpm forward and reverse. Conyeyor drive: | Electric motor, 25 hp, 440 v, 60 cycle, explosion-proof. : { Functional control: ! ; Six hydraulic motors, hydraulic selector-valves, infinite control, { pressure checks, reverse flow, two pressures ~ high and low. . : ! Heat exchanger system: Oil to oil, oil to antifreeze, antifreeze to air. 12. PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD TUNNELING OPERATION Operation of previous seasons , Prior to the main tunneling operation the site was explored, the camp was constructed and a temporary portal was erected for safety, since tiié steep, unstable man-made slope could rea- sonably be expected to interfere with the operation. - There wus a trial period for the Alkirk Continuous Miner. The trials were conducted in var- ious machine configurations with 2.1 m (7 ft) and 2.4 m (8 ft) main cutter diameters. Both cutting speeds (10 and 15 rpm) and several types of cutting tools were tried. In one case, the teeth were so positioned that the whole tunnel face was cut without leaving any ridges; in another, the teeth were spaced to leave ridges which broke off periodically without the expenditure of cutting enery. The result of these trials was a 45.5-m (155-ft) tunnel. As far as possible all preliminary observations are incorporated into the present report and may be found under appropriate headings. Main tunazeling operation Volume of work. In 1965 tunneling began at 45.5 m and proceeded to 110 m (856 ft). Full attention was given to the mining cycle, performance of machine and operator, power use, and the interaction-of various elements. The data summarized below were collected on special shift reports. . Data on equipment maintenance were collected separately. . Operational cycle. The Alkirk machine is called 2 continuous-cycle miner. The cycle begins with extension of the pilot tubes and rotational cutting of two pilot holes. The pilot tubes are anchored in their holes by expansion of two packers consisting of massive rubber rings. The actual mining begins with the starting of the inclined conveyor which removes the debris and cuts the lower cusp, starting of the upper cusp cutter together with the main cutting arms, and applica- tion of face thrust by a gradual retraction of the anchored packers. The rock (or in this case, permafrost) cut by the arms, cusp-cutter teeth and lower conveyor falls down directly in front of the face where it is picked up and transported to the rear. The cycle is complete when the pilots are fully retracted; it is then repeated by cutting another pair of pilot holes, etc. As seen in Figure 8-the cutting tools were extended on special tool holders. This shortened the stroke of the pilots, but was necessary in permafrost as will be evident below. The whole cycle takés about 15 minutes in permafrost, and four such cycles result in 2.4 m of tunnel, pro- vided that all parts function perfectly and haulage capacity is adequate, - The available haulage equipment did not fit under the elevating conveyor and the machine produced more waste than could be removed. But these drawbacks did not detract from the purposes of the research project which were evaluation of the mining method and study of the tunneling pro- cess, not efficient production of permafrost tunnel. - During the two seasons of operation, it was found that the expansion factor (the ratio of volume of disintegrated material to original volume) was {rom 2.45 to 3.6, depending upon the amount and configuration of the cutting tools. Most of the tunneling was done in a configuration providing the lower, more advantageous expansion factor. The Joy 10CS-AC Shuttle Car performed well but its capucity of 9 yd’ was insufficient for one “complete cycle und was a source of delay. Attempts to continue mining between haulage trips failed since the expanded loose material, occupying a larger than in-place volume, threatened to bury the machine. Further delays were caused by the need to insert another machine, a Joy 8 BU- AC front loader rated at 1.75 yd’/min, between the miner and the shuttle car to handle the material removed by the miner. - PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 13 The whole arrangement of mining equipment in the tunnel is shown schematically in Figure 9. Table II] summarizes pertinent haulage data. ‘ Table Ii. Hanlage data 1, Requirements to mine one cycle Nominal ume* . 1S min Tunnel length . 0.61 m (2 ft) Volume of material in place |» 3.9 m?(5.1. yd’) Expansion factor 2.45 , Volume of material to be moved in one cycle 9.51 m* (12.5 yd?) Average time to load one sbutde car 6 min Average time to unload one shuttle car : 4min 2. Ratio of mining time to total operation time Ot 0.500 SO ft 0.428 : 100 ft 0.375 150 ft 0.316 200 fr 0.250 250 ft 0.231 300 ft 0.214 360 ft 0.207 EEE * Time without hauling trip delay. i t ; i i Figure 9. The arrangement of equipment in the tunnel. 14 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD Operating the machine ‘required an average of 113.8 kilowatt-hours per linear meter of tunnel A (34.7 kwhrt/ft). This included all equipment: miner, front loader, shuttle car and ventilation plant. : The consumption varied from 82 kwhr/m to 208.3 kwhr/m (25-63.5 kwhr/ft) owing to the need for long warm-up idling of cold equipment or idle run for adjusting and for packer slipping (see below). A -All three machines in the tunnel operated on trailing cables. ‘The shuttle car had a servo mechanism-guided cable drum which would wind and lay out its cable unattended. . The cables for the miner and front loader had to be brought forward manually, an operation requiring an estimated = 5% of the total man-hours. Operation of the miner requires 183 m’ of air pressurized to around 8 atm (120 psi). The air is needed to remove the pilot bore cuttings und to cool the anchoring packers to enSure a firm hold. Ventilation to supply fresh air and remove heat generated by the machines was also needed for efficient operation. ; _ The last step in the whole operation was dump handling. Normally there are three possible methods for dumping waste materials in a tunneling operation: dumping downhill with an ever- extending ramp, either parallel or perpendicular to the slope; conveying uphill (in this case the operation becomes a stage of haulage such as open pit mining); and handling the muck on grade level. The topographical situation at the tunnel site called for handling on grade. Several methods . were tried: “1 Dumping individual shuttle car loads over a field about 70 x 140.m (200 x 400 ft) and spreading by bulldozer ar the end of two shifts. This method was satisfactory since the following summer melting removed most of the material. 2, The gradual buildup of a 22° ramp by end-dumping from the shuttle car. Allowing the ramp to grow to a height of 1.5 m resulted in haulage delays. Such a ramp had to be removed with a bulldozer. Function and performance Framework of development. The framework of the present research was the search for and evaluation of rapid methods of permafrost excavation for military purposes. A new method incor- porating the revolutionary pilot pull principle was selected and great attention was given to its performance and potential. Observations confirmed that pulling the machine into the face instead of relying on weight or having bydraulic rams working against tunnel walls results ina general. as lightening of construction, increased mobility and high performance rates. : s It is emphasized that the test vehicle was a first generation machine with many mechanical deficiencies. The overall performance was found to be affected by both the machine's functions and deficiencies and the new enviroament - warm permafrost - in which it was working. The prop- erties of the permafrost (warn, fine-grained, supersaturated) together with a tooth design and cutting speeds unsuitable for the material led to a situation where the pilot pull principle of face- crowd could not be shown to its-full advantage. : With a continuously operating machine in combination with an adequate waste disposal system, the costs of a tunneling operation similar to the present one might very well be below those of any conventional mining system. It must be remarked, however, that cost in a military operation often becomes subordinate to mobility, speed, simplicity of operation, and relatively low weight. PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD - 15 Response of machine to environment. The pilot boreholes cut into the face at the beginning of each cycle are only 1 cm larger than the packers before expansion. Axial pressure on the packer rings expands them toward the walls‘of the hole Providing anchorage. Since the fine- grained ice-saturated silt has’a high tempergture, very close to zero C, heat leaking along the Pilot tubes was found to be warming it to a degree where rapid creep occurred, Refrigerated compressed air was blown Continuously through the packers but the benefit was only moderate and diminished as tunneling progressed. Once the anchors failed, it required 2 to 3 hours to cool the soil to a temperature at which it was capable of holding the packers in place, : : The heat generated by the machine and rejected into the tunnel resulted in an additional ventilation requirement. A 12-in. Collapsible hose was installed and outside air was blown into the tunnel. The hose terminated against an automotive radiator installed in the antifreeze circu- lation system of the Alkirk miner. However, the air traveling through the hose gained up to 3C, depending upon tunnel length. An increase in efficiency was noted with the installation of a 6-in, Tigid suction pipe to remove air from the vicinity of the machine, In general, ventilation demand in permafrost tunneling exceeds that otherwise needed, for 5 its main purpose is removal of reject heat. Heat removal from a working machine by ventilation may be considered inefficient but no other methods are as convenient. Table IV gives a rough estimate of ventilation needs at two different tunneling rates, made on the basis of power consumption. : Table IV. Ventilation demands forthe Alkirk excavation system as related to ambient temperature and tunnel cutting rates, ———Ventilation demand i Cutting rate Cutting rate Outside air temp (1 m/hbr) (2 m/br) -10C 425 m’/min 900 m/min 215 275 550 -2D . 186 350 -25 155 275 , -30 120 270 35 100 200 -40 80 175 -45 60 150 -50 40 120 ——-—-——__ eee Table IV is not based on field data but on a simplified assumption that the machine rejected all its heat into the surrounding air which had to be removed at ever-increasing rates as the ambient temperature rose. Unfortunately, the experimental work did not afford either sustained Cutting at either of the two rates or ventilation sufficient to remove the heat generated. 16 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD PLYSCORE See aT Hine mrto & Toa” vost A's tect ms WITH INSULATION - ecrween Purw00D, SMEAT ooG ® TUNORA PORTAL = t x 3 EXTENSION Z [HBUL READ ; ye uy ace | > ~ STEEL. ete —F" cawvenr | 7 ENTRANCE PROFILE ¢ SYMMETRICAL coLvERT INSULATIO (DROID 26'-1" PANEL 2-072 6-1" PANEL “swcs 1 & DOWN” > HINGE HINGES: S-6"s Tat" PANEL “swmes wi” RUBBER SKIRT BULKHEAD SECTION Figure 10. Portal structure Special construction in permafrost tunneling i Se : i = Em 6. Portal. Portal construction, a stage separate from the rest of tunneling activity, is an important and inevitable part of any tunneling operation. Unlike conventional tunneling, a tunnel portal in permafrost has its function extended to summer heat protection. , For the Alaska Permafrost Tunnel, a vertical face was excavated into the slope and 5.4-m (18-ft) diameter corrugated steel culvert was inserted and placed against the face, insulated, and cut flush with the slope. Spaces were backfilled and then the cover part of the culvert was back- filled with gravel. The slope immediately above the culvert was protected by radial brine pipes “for artificial freezing in case of a catastrophic thaw. The steel culvert was extended by a semicircular wooden structure to deflect rain and any material sliding down the unstable slope. Inside the portal structure was an insulated wooden bulkhead with composite doors. Figure 10 shows the portal structure as it was built. PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD “17 € SYMMETRICAL TUNNEL AFTER TRIMMING WITH IORU 78 RO BARS Sway BRACING, | | i } 8 FOUNDATION 2" PLATE |i 672 2-6" WOOD GRILLAGE CROSS SECTION ’ “SECTION AA Figure 11, Arch roof supports. Arches. To make the permafrost tunnel safer, nine welded steel arches of 6WF 25 sections were installed in the first 8.6 m ofthe tunnel (Fig. 11), The arches were designed to yield rather than rupture should a full overburden load suddenly develop, and were intended to protect against toof settlement. The measure was an added safety feature for the specific case, since the tunnel was to be driven into an unstable man-made slope in an area where earthquakes are common. Standard yieldable mining arches were not used as the profile of the tunnel was incompatible. ‘The narrow’space between arches and permafrost was lagged with 2 x 8 timber and grouted with moist sand. Tunnel configuration. ,Normally, a tunnel driven into a warm rock under conventional condi- tions is likely to be subject to water Seepaze or flood. For that and other purely mining engi- neering reasons, it is customary to design and to drive a tunnel at an upward gradient of a few degrees, . ; From the beginning of the operation, partially due to difficulties with horizontal and vertical alignment, the Alaska Tunnel was driven in defiance of that mule (see Fig. 12). Its shape © ~ differed from that of conventional tunnels inthat it had a depression of the floor at the portal to accumulate cold air. It was hoped that this would result in colder permafrost near the portal which might have been beneficial since the oval section of the tunnel had to accommodate move- ment of men and machines. For convenience and safety the power cables, air hoses, and telephone lines were placed in slots cut longitudinally into the lower part of the tunnel. As an additional safety measure, a heat exchanger was placed in the tunnel at the highest point in the portal area. It was connected with a compressor installation to be used if the portal area became dangerously warm, + meee neces 6 ae ane a COR, Ae Se ee Se fe ame A 8 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 260 z 250 < = 240 a J 230 : sta +00 #00 "> 2400 3+00 TUNNEL PROFILE ¢ SYMMETRICAL 1 | 12" 6" FORCED air TuRI \ RCE | vENTu tC ¢! TELEPHONE O STORAGE ROOMS wile AT STA.1+50 8 | 3+50 ane — TRAILED SHUTTLE : : LW CAR CABLE i ~~ ° MINER CABLE CONTROL CABLE CABLE SLOT COMPRESSED AIR CuT with IoRu TYPICAL TUNNEL CROSS SECTION Figure 12, Profile and cross section of the Alaska tunnel. PERFORMANCE OF THE MINER Excavation by a continuous mechanical method Potential performance of the machine. Observations on the operation of the machine led to the general conclusion that the Alkirk Continuous Miner is potentially capable of sustaining an~ TT excavation rate of several meters per hour. Remedy of certain structural and mechanical defi- ciencies (to be discussed later), the provision of heat removal, and an adequate supply of power and refrigerated compressed air are all prerequisites. An adequate continuous haulage capacity is very important since without simultaneous debris removal the machine buries itself in its muck pile in a matter of minutes, Observations on cutting strain and power consumption. One problem needing a special { approach was observation of the dynamic cutting forces as related to power consumption, face’ pressure, pressures of hydraulic fluids, etc. This was done by means of strain gauges, pressure transducers and recording wattmeters ina system designed by G.A. Brewer (1965). The cutting force transducers consisted of a standard Alkirk tool holder, undercut at the proper place, and two strain gauge rosettes applied in a way that eliminated the possibility of mechanical damage and influence of thermal shock. The calibration was by application of known loads in the usual man- ner (Fig. 13). Seid PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 19 Figure 13, Cutting force transducer arrangement. Since the Alkitk cutting tool revolves around a shaft the data from the load cells were transmitted by radio into the tunnel where they were recorded simultaneously with all other infor- mation. * The machine's hydraulic system was monitored by two GEC fast response resistance type pressure cells at the face pressure and packer pressure lines. Finally, power consumption was recorded at all stages of the investigation. The measurements were made by G.A. Brewer (1965) under contract with USA CRREL. He reports an uverare of 64 kw power consumption during cutting and 32 kw idling, packer pressure 1400 psi, face pressure (crowd) 500 psi, anda cutting force between 500 und 1100 lb. During the miner operation, sharp peaks of face and packer pressure that could have heen detrimental to the hydraulic system of the machine were recorded. Brewer expressed concern that high pressure surges are most probably the cause of numerous hydraulic leaks, C ring failures and line’ bursts. Labor requirements. The personnel occupied with experimental tunneling consisted of two engineers, 6ix technical personnel and the project leader. Normal production tunneling in. a‘sim- jlar environment would require one mechanic, specially trained to operste the miner. one helper, doubling for outside work, such as compressor-plant help; one shuttle-car operator, one front- loader operator; and one general helper. An additional man would be needed to take care of out- side -work. ; It is important to mention that trials showed that increasing manpower did not increuse | productivity. An extra mechanic on the crew did help during repair of the miner. Employment of more than two repair men is not beneficial owing to crowded conditions at the tunnel face. - tee ee ’ j } 20 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD - Much depends on the crew's training. In addition to being a certified mechanic, the miner , operator must have at least three months of specialized training. His helper must be a mechanic, who could'be trained on the job. The shuttle-car and front-loader operators may be heavy-equip- ment operators who could be trained in the course of one day. An experienced minet should operate the muck pile outside. ” Other observations on the machine. Operation’ manuals, manufacturer’s instructions and blueprints of the Alkirk Continuous Miner indicate a very complex hydraulic system which in the prototype machine under test was prone to frequent failure. Most frequent were air locks in valves, broken lines and fittings, failures in hydraulic pumps and motors, and Quid leaks in pilot tubes. Maintenance records for 30 shifts Gabout 22 hours actual mining) show 9S gallons of hvdraulic fluid was lost. Specialized testing equipment and special traiming for the mechanics would have lessened lost time. Another deficiency of the hydrauhe system, insufficient cooling of the fluid, resulted in overheating of pilots and soil, ind slip of anchor packers, It seems plausible that the frequent line bursts and other failures were due to the extremely high peaks in hydraulic Nuid pressure aS observed and reported by Brewer (1965). The failure of packers to provide support for crowd pressure was responsible for 2 large percentage of the mining time loss. As mentioned, the cause was cumulative: packer design in- sufficient for local permafrost, need for excessive crowding (see below), insufficient heat removal capacity, and frequent idling due to insufficient hauling capacity. ‘ Two other construction deficiencies were a frequent source of delay during the main tunneling procedure. One was the tracks of the machine which were inadequate for walking on ordinary surfaces. The machine had to be moved on plywood to prevent tearing the tracks. In several instances tracks were damaged when a small foreign body such as a pebble became jammed between cleats. Serious deficiencies were found in the alignment system. For correctional horizontal align- ment, the design procedure requires application of additional face pressure on the cutter opposite the direction in which it is desired to turn. Besides being ineffective, this is detrimental to the pilot tubes and their oil seals. It was found that the only opportunity to change horizontal direc- tion came at the end of the cycle. The pilot tubes were extracted, the machine was backed away E from the face and realigned in a new direction, and new pilot holes were cut. At times it was necessary to’plug and refreeze the old pilot holes. ‘This technique permitted a correction of a few degrees at a time. . a E } Vergical alignment presented more serious problems owing to the mechanism provided for it. ‘The machine had a tilting device to raise or lower the cutting parts simultaneously. 4 Figure 14a,b shows the alignment for horizontal cutting and a configuration for raising the center- ha k line of the tunnel. The angle is exaggerated for clarity. Note that the dimension of the tunnel (a) is identical with that of the new tunnel, while tilting the overall size of the cut (b). i , Attempts to raise the tunnel by the existing method resulted in binding the machine at the face, bending of pilot tubes.and failures of the upper cusp cutter. . It appears that an arrangement similar to that used in snow millers (the Peter Snowmiller " } J for example) would solve the problem. Figure 14c represents a proposed configuration for straight \ line cutting and Figure 14d shows the cutting mechanism lifted parallel to the axis of the tunnel. Figure 14e shows the configuration for directing the tunnel) downward, 4 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL. METHOD ‘21 Figure 14. Existing and suggested vertical alignment principles. a,b: Existing method, distances a and b unidentical. c,d,e: Suggested mechanism: No change in tunnel dimensions. Another solution would be to widen or narrow the tunnel diameter at will by 1 or 2 cm. The effect of such an arrangement would be much the same as that shown in Figure 14, d ande. Cutting action The main job of excavation was done by two circular counter-rotating windmill cutters set in position to cut most of the oval outline of the tunnel. The description that follows concerns the main action of the machine - the two cutting arms in circular motion. 7 The maximum cutting speed on the periphery of the two cutters is 67m/min (220 ft/min) at 10 rpm; all other parts of the cutters move correspondingly slower. The cutters are armed with standard drag bits (Fig. 15). The teeth on all four arms are positioned so that alternate passes over the face leave a system of grooves and lands (Fig. 16). The 2.4-cm-thick lands broke off from time to time, apparently without a notable expenditure of energy. During an early tunneling stage an attempt was made to cut the whole face without leaving any grooves or lands (Fig. 17). This resulted in formation of fine cuttings, slow progress and overload of the machine. It was concluded that tightly spaced drag bits do unnecessary work, using additional energy to disintegrate the material excessively. The following findings connected with the cutting process are based on direct measurements and experimentation. ; To cut grooves wide enough for the tool holder, a single bit of 5-cm edge width was origi- ‘nally used. The tungsten carbide edge soon began to chip in several places, resulting in an irregular curvature which rendered it useless. But measurement showed that individual chips were about 1 cm away from each other, leading to modification of'a standard drag bit (Fig. 18a). -The finally chosen position of the drag bits in the individual tool holder is seen in Figure 15. 22 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD ” TUNGSTEN : BRBPE oe f YEYEN CUTTING ARM . E k ‘ Figure 15. Cutting arm and individual tool holders. Further observations were made on the wear of the teeth (Fig. 18b-e), When the tool moved a) in such a manner that its steel was not protected by hard inserts, it was quickly worm away (Fig. r 18 b,c). Normally, wear rounded the cutting edge rather than chipped it (Fig. 18d), resulting in i a progressively shallower cut and increased crowd demand, The hard inserts also wore unevenly. . Figure 18e shows a hard inclusion in the tungsten carbide protruding because of differential wear. ° a ', The action of drag bits in homogeneous permafrost is shown in Figure 19, In an experimental slow cut a sharp bit was moved across 2 frozen sample (Fig. 19a). Its initial engagement produced a , | plastically defocmed and compressed area (b), which, when motion was allowed to continue, A ‘ increased until the first brittle chip failure occurred (c). The compressed area disintegrated immediately thereafter. A dull tool tended to ‘‘ride up’” onthe face, requiring much more crowd . force to stay in the face and producing a large amount of smaller, plastically deformed chips A I, PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 23° Ne ae RRR Ee Ee ent mete 4 eunte te Nee teens 4 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD Figure 18, Triple edge drag bits. -_PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 23 a. be ¢ d. e. t eer) g. Figure 19. Drag bit action. \Fig. 194,e,.9. Apparently @ tool formed like that shown in Fig. 19g, or similar, would work better than standard drag bits. Discussion of the property and shape of the dotted line in Figure 19g as well 2s additional considerations on the process of cutting frozen ground evolved into 2 research program beyond the scope of the present paper. ; , Properties of permafrost tunnels Plastic behavior and mode of failure: It is often said that permafrost is a rock material formed from any soil material by frost consolidation of its pore water. From this mining engineer's classification of permafrost, one visualizes a large variety of properties dependent upon temperature and composition. Properties of a large variety of permafrost types are, compared on the following pages with similar rocks cemented by means other than freezing pore water. 2 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD As a cement, ice is weak and under sustained load is subject-to greater plastic deformation than are cementing agents like calcite and dolomite in sandstone and conglomerates. A subsur- face excavation in sandstone; siltstone or conglomerate becomes subject to brittle roof failure before any measurable plastic deformation occurs. But pillars in permafrost fail plastically and such a phenomenon as rock burst is unthinkable in permafrost tunnels over the whole range of natural temperatures, 7 € __Our own observations of deformation in frozen matter began with ice tunnel deformation in the massive ice ofthe Greenland Ice Cap (Swinzow, 1962). It was found that clean ice may deform slower than mixtures of frozen rock debris. Further observations indicated some types of perma- frost with little or no plastic deformation: In three years a room of 65-ft span, dug in cold, boul- dery, unsaturated (approximately 25% moisture) permafrost, did not deform in excess of measure- ment error. Permafrost of coarse material with dense packing does not readily deform plastically. Conversely, fine grained, supersaturated permafrost especially at high temperatures has a tendency to deform plastically. It appears that the solid soil particles weaken the ice. Observations at the Alaska Experimental Permafrost Tunnel (Fig..20) showed noticeable deformation with only a small amount of overburden. Since the tunnel was dug under only gently sloping terrain, the perceptible difference in deformation rates could be tentatively explained only by the temperature difference between the middle of the tunnel and a point toward its work face or portal. The permafrost temperature difference between the two points was close to 1C while air temperature differences varied during the observatioa period, the point at 350 ft always being warmer. - The plastic behavior of local permafrost as well as experiments with explosives indicate that brittle roof failure is improbable under the influence of high velocity shocks such as large explosions at the surface. Although often weaker than materials cemented by other means, perma- frost provides a safer roof under certain overburden and span conditions (Livingston, 1960). Ground temperatures around a large cavity change with time. If the opening of the cavity is higher than its main space, its temperature will decrease and be lower than the annual average, Conversely, caves with a main room above the entrance are warmer than the mean annual tempet- ature. In the first case, the cold winter air settles down in the cave.and is not readily removed during the summer. As soon 2s the outside temperature becomes lower than that of the cave, air exchange begins. This is how so-called ice caves form in moderate climates. This effect, use- {ul as it is, is not being utilized sufficiently at the present time. pening in permafrost is subject to air currents that reverse their direc- tion with the change of seasons. Anemometer observations in the Alaska Tunnel indicated that in the winter the relatively warm air moved along the roof toward the portal with maximum veloc- ities reaching 2.5 km/hr and was replaced by cold air moving in along the floor. The simple measure of closing the portal tightly and reducing the inside activity to a minimum in the summer was sufficient to accumulate some heat sink capacity. was inadequate since the air forced through the pipes arrived at the ees warmer than the outside temperature. After the final excavation season a vertical shaft was drilled at the end of the tunnel. During the cold winter months it provided a strong chimney effect with rapid air exchange and effective cooling. The air circulation in the closed tunnel is limited to vertical convection between Moor and roof. Sublimation. Stable ice can exist in contact with air only if the sir is saturated in respect to ice molecules. In cases of dry air (low relative humidity), ice “dries out.’’ Sublimation is well understood and studied; its rates depend upon interface shape and ice vapor pressure (and therefore temperature). If at a given temperature and low air humidity, sublimation produces an increased amount of vapor in the vicinity of the interface, free air movement adjacent to it removes A nearly horizontal o Artificial: ventilatioa end of the tunnel several degr: a anol. aon AOL PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 2 : : O HORIZONTAL STA. 1*50 . VERTICAL SHORIZONTAL STA.3*50 |. verTICAL DEFORMATION, inches ° ' 2 3 4x10> TIME, hours Figure 20, Relation of time to deformation at sta. 1450 and 3+50. the vapor concentration gradient, thus keeping the process of sublimation at a constant, rather than a decreasing, rate. Permafrost surfaces, consisting.of many solid particles of soil alternating with ice, are also : subject to sublimation. In the tunnel a smooth, firm, freshly cut surface became dusty after a short time. The thickness of the dry layer increased rapidly, reaching 1 to 1.5 cm in a week. The layer was firm but very friable and strong air currents disturbed it and made the tunnel air dusty. The rates observed in the field, 2s well as those reproduced in laboratory studies (Luyet, 1967), could not be made to correspond to any rigorous prediction. In the field, temperatures, air humidities and ventilation rates changed almost hourly. Since one purpose of the laboratory work was to set up a standard condition close to the average natural one, tests were conducted at -2C and 50% relative humidity. The tests revealed that the permeability for water vapor was constant and that sublimation occurred at decreasing rates. The increased thickness of the dry shell was apparently the main factor bringing the process to a halt. Observations in thetunnel indicated that:an undisturbed dry dust shell may reach 14 cm in about 65 days, by which time the process is slowed down to an imperceptible rate. Earlier work on prevention of sublimation from frozen ground surfaces revealed that simple measures such as spray painting, lacquering or coating with 2 non-drying petroleum product were sufficient to arrest the process fully over a period of five years (Swinzow, 1964). Causally unrelated but intricately connected with sublimation is the process of hoarfrost formation in a closed permafrost tunnel with very little outside air entering and only limited human activity underground. ; . The Tuto, Greenland, permafrost tunnel is an example. The lower part of the tunnel is drying out by sublimation while hoarfrost grows in thick layers of crystals all over the upper part, The tunnel is dug on a gentle rise and the sharp demarcation line between drying and deposition is horizontal. In the portal area it is about 0.75 m above the floor and merges with the floor at 164m. The continuously growing masses of hoarfrost crystals on the roof fail uhder their own aeeeonen 40 me, <n tee cea i eee cet eee ee eee ee ee ae ee ae re ee meee ore ee ee a a ts ot tenn 6 a PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD weight and land on the floor where they are subject to sublimation. This circulation of moisture is another check of sublimative drying of permafrost below the horizontal dividing line. Obser- vations using ammonia fumes as markers revealed convection of air between roof and floor, the upward stream being in the middle of the tunnel. Apparently, it is a double convection cell with a maximum Mow velocity of 0.7 m/min. t Similar phenomena will probably be observed in the Alaska tunnel when active research ceases and forced ventilation is discontinued, ~ 7 SUMMARY _ Military uses of an excavation in permafrost Previous investigation has indicated that frozen ground responds poorly to disintegration by all types of explosive application. In subsurface exploration it is the poor powder ratio; in surface blasting it is the low yield and only moderate effect of bombing and artillery (Livingston and Waldron, 1965). ~Most important, however, is the specific response of roofs in subsurface excavations to blasts . set off at the surface. The danger of brittle roof failure is, in the writer's opinion, minimal since brittle response of permifrost during short duration loading occurs only over a limited range of stress. Unless a shelter in permafrost is very shallow, so that overburden thickness is close to span width, brittle roof failure is unlikely as long as the roof contour is outside the direct fracture zone of the explosion. Observations in Greenland conducted on cold, bouldery permafrost with a span of 20 m demonstrated a lack of response to explosive shocks from the surface as well as free blasts in- side the tunnel. The flexibility with which the frozen state may be put to use in excavations is also attrac- tive for military purposes. Using a type of ‘concreting masonry’’ work, repairs of all sorts may be successfully performed in permafrost tunnels (Swinzow, 1964). Should roof crevices form in the process of excavation, they are easily repaired by use of a sand-water grout, which freezes back, rendering the needed strength and safety. Where plastic deformations are taking place, such as the present tunnel, they either could be accounted for in advance, oc arrested by artificial means (such 2s chilling by winter ventilatioa). Ease-of excavation is another attraction for military use of tunnels in permafrost. It has been demonstrated that a comfortable personnel shelter can be constructed in a cave dug in a frozen material. Russell (1966) described in detail an experiment where an insulated camp with all facilities was constructed in an ice tunnel in the Greenland Ice Cap. With suffi- . cient insulation, room temperatures inside the shelter structure can be kept well above those outside, With sufficient ventilation the maintenance of low temperatures in the tunnel outside the building is not a secious problem, The constructioa of large command posts, bulk fuel storage caves, and warehouse facilities in permafrost appears to be feasible and should be investigated. Tuneeling method The most striking feature of the Alkirk Miner is the novel pilot pull principle with its advantage of less weight and incipient increased maneuverability. The machine also has rela- tively low power consumption compared with other coatinuotis mining systems. The rates of cutting. obtained were promising. To be practicable, the peinciple must be applied with compatible, PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 29 eliable equipment. Modifications of the machine for use in permafrost.should include redesign of the nydraulic system, vertical and horizontal control and tramming method, an improvement in anchoring and a heat exchanger. Cutting speeds are insufficient for the perennially frozen silt. The design of the drag bits also requires consideration although the same bits ysed on a faster cutting machine performed yetter regardless of advanced wear (see Fig. 21). It’uppears that the design of special] bits perhaps such as suggested in Fig. 19g) requires consideration of varying cutting speeds of the machine. The application of the pilot pull principle is highly recommended for possible future excavations in perennially frozen silt deposits. cats nena Rene ne On etn nee en ee Ree eee ee ene AR ROLE Ae ene am ee _ Figure 21, Chain saw teeth of the 10 RU miner. 30 PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD Some reservations The Alkirk Continuous Cycle Miner is a ‘‘first generation’’ machine originally developed for excavation in coal and soft rock. Its applicability to warm permafrost was the main purpose of the present application. For this reason, technicalities of construction have been kept to the minimum necessary to explain the principle, its advantages, and its weaknesses. The performance of the standard coal mining equipment used in the project may be stated as satisfactory, its detail- ed description is beyond the scope and need of the present study. : The overall conclusions were reached under the handicap of incompatibility of standard mining equipment with the Alkirk Miner. For example, the shuttle car used for debris removal (Fig. 9) was incompatible with the machine in two ways: it did not fit under the conveyor and its capacity to remove cut material was far less than the miner’s ability to excavate, that is, to produce spoil. The mechanism employed between the two machines - the front loader - corrected only one deficiency, the dimensional incompatibility. The Alkirk Miner had a low cutting speed and was armed with improper cutting tools. This necessitated excessive crowding which caused frequent anchoring failure, The need for refrig- erated compressed air, frequent overloads, and failures in the hydraulic system were doubtlessly connected in part with the above conditions. It is concluded that in order to use the machine to full advantage it should be thoroughly redesigned to a second oc perhaps a third generation model. Despite all reservations concerning performance during the tunneling experiment, it is recog- nized that the machine has a series of progressive features, its relatively light weight and low power requirement being not the only ones. The pull-in principle is revolutionary and is potentially advantageous. This is connected with possibilities of better maneuverability. Hydraulic drive will potentially provide infinite control. = It cannot be overemphasized that to make the machine work in permafrost, a large research and development effort would need to concentrate on steering methods (Fig. 14c,d,e), anchoring the pilots, improving heat removal, and toughening the hydraulic system. Increasing angular cutting velocity and, especially, designing cutting teeth adapted for the various linear cutting velocities appear to be important. LITERATURE CITED , Abel, Joba F., Jr. (1960) Permafrost tunnel, Camp Tuto, Greenland: U.S. Army Cold Regions Research and Engineering Laboratory (USA CRREL) Techical Report 73 (AD 652712), Brewer, Given A., Jr. (1965) Dynamic cutting forces and hydraulic pressures. Excavating perma- frost with Alkirk Miner. Brewer Engineering Laboratories, Inc., Marion, Mans.. Research Contract Report 311. USA CRREL Intemal Report 57, Corte, Arturo, E. (1962) Relationship between four gound patterns, stucture of the active layer, and type and distribution of ice in permafrost. -USA CRREL Research Report 88 (AD 430193). Livingston, Clifton W. (1960) Fundamentals of arctic blasting. Proceedings American Society of Civil Engineers, Construction Division, vol 86, p. 1-9. and Waldron, Howard.L. (1965) Penetration of projectiles into frozen ground, USA CRREL Technical Report 93 (AD 616348). . Luyet, Basile Z. (1967) Study of rate and mechanism of sublimation in permafrost silt USA CRREL Intemal Report 24. wh + PERMAFROST TUNNELING BY A CONTINUOUS MECHANICAL METHOD 31 LITERATURE CITED (Cont) _.sCoy, John E. (1964) Selection and modification of mining machine to mnnel in permafrost. USA CRREL Technical Note (unpublished). | (1964) Use of mechanical system to tunnel in permafrost USA CRREL Technical Note (unpublished). Mertie, J.B., Jr. (1937) The Yukon-Tanana regions, Alaska. U.S. Geological Survey Bulletin, vol. 872 p. 200-275, éwé, Troy L. (1955) Origin of the upland silt near Fairbanks, Alaska. Geological Society of America, Bulletin, vol. 66, no. 6, p. 699-724. ussell, Frank L. (1961) Under-ice camp in the Arctic. USA CRREL Special Report 44 (AD 653150). , Sellmann, Paul V. (1967) Geology of the USA CRREL permafrost tunnel, Fairbanks, Alaska. USA CRREL Technical Report 199 (AD 660310). _winzow, George K. (1962) Investigation of shear zones in the ice sheet margin, Thule area, Greenland. Journal of Glaciology, vol. 4, no. 32, p. 215-229. (1964) Tunneling in permafrost I, USA CRREL Technical Report 91 (AD 435608). (1966) Tunneling and subsurface installations in permafrost. In Proceedings, First [International Conference on Permafrost, N.A.S.-N.R.C. Publication 1287, p. 51% $25. Taber, Stephen (1943) Perennially frozen ground in Alaska, its origin and history. Geological Society of America, Bulletin, vol. 54, no. 10 p. 1471- 1497. ‘ e APPENDIX A OBSERVATIONS ON A 10 RU COAL MINER In addition to the investigation of the Continuous Cyclic Mining System described in the text, a standard 10 RU Mining Machine was subjected to a brief test. The machine is normally used in long-wall coal undercutting and in other specialized underground work. _ Tne Joy 10 RU Cutter is a self-propelled, cable laying, tire-based machine working ona chain saw principle. -It is powered by two motors: a 30-hp motor driving the hydraulic system and a 50-hp motor driving the chain saw. Both are 440-v ac. The machine has a variable tram speed, the maximum being 70 m/min. Its cutting speed of 183 m/min was successful, in the way permafrost disintegrated. One advantage was the extreme simplicity of operation — the 10 RU could be operated suc- cessfully after only a few hours of training. The versatility of the machine permitted its use for a variety of functions such as trimming the tunnel profile to a desired shape, cutting notches in the wall of the tunnel for cable and pres- sure hoses, and excavating large rooms with flat walls. Although the purpose of the machine is not tunneling, an attempt to do So was successful. The machine was used in a discontinuous cycle, e.g. about 2-m-deep cuts were made at first vertically along the edges of the face and then horizontal cuts were made every 20 cm beginning at the bottom. In this way, the face advanced 2 m per cycle after the front loader and shuttle car removed the debris. _The-chairi_of the machine was armed with drag bits essentially of the same size and config- uration as those in the Alkirk Miner. Apparently due to the high cutting velocity, the 10 RU pro- duced debris that was more uniform and of coarser size thanthat produced by the Alkirk Miner. While particles liberated by the teeth of the Alkirk Miner were between 2 mm and 1 cm, and the whole muck pile contained a large amount of dust, the cuttings produced by the 10 RU were from 3 to 7 cm in size with a very small amount of dust, indicating a more efficient operation. Correspondingly, the expansion factor in the muck pile ofthe 10 RU Miner was found to be low (1.8) compared with that of the Alkirk Miner (2.45). Observations on the wear of cutting teeth together with the material removed indicate that the Alkirk machine ‘‘cuts"’ by slow induced failure; the faster 10 RU cutting speeds ensure brittle failure with all its advantages, Furthermore, since the expansion factor could be kept smaller with the 10 RU, its cutting process seems tobe moreadvantageous. (It is emphasized that a lower total specific surface of the cut material is always advantageous.) Since the latter parameter is in direct relation to expansion factor, special observations-were not needed. Also of interest is the low dependency of the machine's performance upon the condition of its teeth. While the progressive wear of teeth on the Alkirk machine during the slow cutting was accompanied by increasing crowd demand and higher packer pressure with all its consequences, enter ent fh nace ecasesieacenanr| imasaendimmeeesueaceteemsyaae nine mo | | | [ os "| =a iF c 4 APPENDIX A partial or full loss of cutting edge of the teeth of the 10 RU produced virtually no adverse effect on performance. Figure 21a shows the normal sequence of,tooth wear in the Fairbanks silt. The last tooth performed as well as the others did. Figure 21b shows an enlargement of the third from left tooth indicating its mode of disintegration. ‘5 In some cases, defective manufacturing resulted in absence of clearance (Fig. 21c) but subsequent wear corrected the situation. : Sometimes improper insertion of tips resulted in poor performance (Fig. 21d). For example, one tooth with a poorly set edge, all others being proper, generated enough vibration to disengage the saw from permafrost. : PRODUCTIVITY OF OPERATION Since the construction of the tunnel was not the sole purpose of the research (neither was a test of the machine per se), a precise prediction of its efficiency is impossible. The tunneling equipment had to be engaged in tandem (see Fig. 9). The Alkirk Miner, oa -the extreme right, combined two functions, cutting the face and elevating the cut material with its conveyor. Since the shuttle car would not fit under the Alkirk Elevating Conveyor, the Joy Front Loader had to be switched in between. Finally, the dump conveyor-equipped shuttle car picked up the. material and transported it to the muck pile. The equipment was supplied with power as shown inthe left diagram of Figure 9. The right diagram shows the routing of compressed air to the miner and venturi pump (not shown) used to evacuate warm air from the machine. In addition, there was a string of lights and a field telephone close to the face connected with the powerhouse and outside. This set-up was partially described in the maintext, Accurate prediction of production performance is difficult but during the report period the machine produced 63 m of tunnel in 21 hours of operatioa. The performance of the equipment was observed and data collected in order to detect possible weaknesses. All malfunctions and breakdowns were noted and categorized (Table AI). An indicator of the extent of failures is the down-time during repairs. , Rebuilding and redesigning certain components of the machine would undoubtedly improve the function of others. For example, a better design would eliminate packer slip; elimination of hydraulic hammer effects would result in elimination of many component failures, All mining was accomplished within 30 9-hr shifts. Since six production personnel were employed on the average, 2 total of 1620 man-hours was to account for productivity determination. Besides the 910 man-hours’spent on repair of mining equipment and 208 man-hours on mining, a total of 50 man-hours.were spent on maintenance. Table AII gives a breakdown of manpower utilization. Note that the total number of work hours (time) is larger than time available, since most of the activity in maintenance proceeded simultaneously. APPENDIX A . 35 Table Al. Mining equipment failures registered during the tunneling operation (from shift reports) . ‘ eee = eT ‘ rey Failure : Repair time (br) hh atta Alkirk Miner Upper cusp cutter: Axis shom off , 62 Tom drive chain ‘ 11 : 8 E Shom off support 2 : 82 te B Hydraulic system: : E Line leaks and broken lines se. ; , Broken pumps and motors 47 | -= Valve failures and air locks 2 i : = { = E 106 : _ a { Mechanical failures in mechanisms: t ; i Tom thrust rings : E Bends in pilot tubes Broken packers Tom tracks Torn bit holders BlB ean Elevating conveyor: Motor replacement Realignment, tooth replacement, Rubber skirt replacement © yro~ Miscellaneous: Front scraper blades bent Operavonal failures without breakdown: - Packer slipping 3B Cleaning plugged pilot mbes 3 Realignment of miner 30 V1 ie Shuttle Car : “Cable torn out Cable insulation embritued by frost 1 Front Loader Frozen lines Frozen conveyor Broken gathering arm bearings Hydraulic line failure Nle Sow ine cn ce ee meee fate ee ammaen ee 36 APPENDIX A Table AI‘(cont’d) Failure Repair time (hr) Stationary Equipment : » Malfuncuons in refrigerator 10 Power failures 3 13 Total repair ume: 7 34 Repair in man-hours ; 910 Table All. Manpower utilization during 30 9-br shifts of mining Time (hr) Labor (man-hr) Mining 33.6 207.6 Repairs (Table AI) 364 910 Maintenance : Miner 143 370 Snuttle car 14 33 Front loader 24 58 Aboveground equipment 19 41 7 597.6 1619.6 Available (270) (1620) ee Besides illustrating the labor utilization pattern, Table AII indicates that a substantial reduction in only two items, repair and maintenance of the Alkirk Continuous Mining Machine, could easily improve its productivity (not mining rate) by at least three times. The personnel operating the Alkirk Miner did not have any specialized training. It is felt that speciadly trained people would not be able to increase the productivity of the machine, but would be better than untrained people in making repairs and adjustments. Techatcal Report Gl JANUARY, 1964 Tunneling in Permafrost, Il by George K. Swinzow U.S. ARMY MATERIEL COMMAND COLD REGIONS RESEARCH & ENGINEERING LABORATORY HANOVER, NEW HAMPSHIRE | b PREFACE This report covers 1960 work as Corps of Engineers Project 39Be Tunneling in Permafrost. The tunnel was begun in 1959 as a project of the Applied Research Branch, with Mr. John F. Abel as project leader, and continued by Dr. G. K. Swinzow for the former Basic Research Branch. The latter part of the work was under the guidance of Mr. James A. Bender, then chief, Basic Research Branch. This report was prepared by Dr. Swinzow. Field and camp support were provided by the U. S. Army Polar Research and Development Center. SP5 Elmo Bradley, USA PRDC, was shift boss during the 1960 field season. This report has been reviewed and approved for publication by Headquarters, U. S. Army Materiel Command. Ww. Le RO GESSER Colonel, (ZE .Commanding USA CRREL Manuscript received 9 June 1961 Omens es iB _ CONTENTS “ Preface ----- cece rrr cree cc cereeee re Summary --+-++- io Intruduction ----cccr errr tee e rer eee General background -+---- Location and environment Permafrost types --- Moisture distribution Temperatures scceee Tunneling operations Cycle of operation sescces Personnel and valine of work ses ec eee ee cee ee eee Moaning equipment ceessercccc ee cee cece ccecce Blasting and explosives - fe Types of explosives: s--+--++ +2 ee rre ee Drill pattern ---++-------- eee eee e- Stenuning +--+ ee cece cre cere cere eee Results of observations ----+-+-++e---- Ventilation and air flow ------- Miscellaneous uses of freezing ---- Description of the tunnel ---------- enn cern rrreene Instrumentation ------------ ee eee ene eee aoe Purpose -ct-ccsseece woceceeee ccecccece : Types of permacrete work done - Roof support ----- eee cece ec eee Floors ------ eee enn nen e eee cenee Bricks andarches - . Beam experiments --------+--°- ‘Optimum composition --++---- Discussion -ccrcrrrerrree Recommendations References -cccc cen mene enone rece nner eennns Appendix A: Skin hardness and brittleness tests errerec-n er nne Al Appendix B: Interpretation of lithological observations -------- Bl ILLUSTRATIONS : Figure i la: Five different compositions of bulk till ---+----e-re ce eee 2 ; lb. Mcchanical analysis of sand lens at about 295 ft -- 2 2. Moisture distribution -ecr-r reece ee ere reer ne ccce 3 ' 43, Drill pattern and shot round -----+----crre rere rrr ncn 5 \ 4; Longitudinal cross section of the tunnel face -- 8 . 5. Air circulation patterns --------+----rr cere 9 6. -Plan of permafrost tunnel ------+crrrrcee eee e ee eeeee 10 7. Furniture and seismograph foundation made from perma- Ce ceeece 12 = 8..Permacrete column supporting loose slabin the roof --- 12 9. Masonry permacrete arch, 560 it from portal ---------- 13 10. Loaded pre-cast permacrete arch, 620 ft from portal ---. 13 11. Permacrete beam experimentS -------cceeeeeeeeneene> 14 Bl. Ravine in which the tunnel is located ------------------ = BI B2. Cross-section of an excavation in the region of the permafrost tunnel -----+- ee nn cnn n nn nnn nnn nnn nnennne B2 B3. E-W profile in the permafrost tunnel region ----------- B3 age, B4. Approximate N-S cross section along axis of the tunnel - B3 Se oh BS. Schematic drawing of the formation of the permafrost : te tunnel area ----- ene neem en en een e nnn een eennneeenne-- | BS —_— vr. TUNNELING IN PERMAFROST, REPORT II oy alis findings held true with’one exception.. A more efficient system of fluid utilization was developed and adopted. Previously, drill water was piped from the surface by ruravity flow, and consequently remained in the pipeline for a long time. Therefore, a righ percentage of antifreeze was needed to prevent freeze-up. This presented a haz- - tard, since the spent liquid covered the floor without refreezing. In the new method, water was brought into the tunnel in a closed tank, pressurized in place from the air = "ine, and injected into the drills. This required'a much weaker solution of antifreeze, =f low as 1:25, and resulted ina safe, dry floor. . rene Drilling time in one cycle averaged from 40 to 60 min. The higher figure resulted cewhen large boulders had to be penctrated. Mucking lasted from lto 3 hr, averaging tbuut 7 minacar. A norinal lO-hr shift would start with mucking following by drilling chen blasting and would be repeated to form two complete cycles. The two ventilating times fell on the lunch hour and shift change. A typical day would result in 8 linear ft of 64 x 7$ ft tunnel — less during crosscutting, room excavation, and other routine jobs. The final average productivity of a double cycle was 5.37 linear ft of tunnel, or 3.7 y@ of excavated material. : Personnel and voluine of work and 2 mucker operators. During each step of the cycle, the men in charge conducted the operation with the remainder of the crew acting as helpers. Using additional men did not increase produc- tivity during regular tunneling. The efficiency of tunneling in permafrost may, however, - be slightly increased by using four crews working four 6-hr shifts around the clock. Such an operation may turn out to be more productive and is recommended where speed 43s more important than cost. 5 : 1 | . Each shift consisted of 1 shift boss, 1 explosives man, 1 drill operator, 2 drillers, . : r : { The volume of work amounted to 109 productive shifts with 19 maintenance and con- struction shifts. Only three shifts were lost because of bad weather. This could have een more had the operation been conducted.at the surface. Once begun, tunneling op- erations in permafrost were not affected by weather conditions. P The total’ amount of permafrost excavated was 1056 yd?. Each mining car was Fifilled to an average capacity of 20ft8, The excavated material was carried out in 2420 : P*mining car loads which shows that the materia] expanded 1.7 times. The total drilling * footage was 15,245 ft indicating that three average holes were needed to remove 1 y@ of | permafrost from the face. ° ' Mining equipment | An 18 in. light mining track system was used. This was found to be most satis- factory fora 6.5x 7.5 ft profile. Under the given conditions, the Type Z (Denver Equip- ment Company) 24 fP ore car was found suitable. Hand-tramming was employed only for a short time at the start of operations. With longer distances, machine-tramming with a Mencha storage battery locomotive was found to be most efficient. The operation, conducted on a single track, did not require any turnouts or car transfer. Side spurs to | various rooms in the tunnel insured mining without an excess of track work. Mucking was conducted with an Limco Model 126 Rocker Shovel. This proved to be a reliable machine, needing a minimum of maintenance. CP-ISL-459 Air Leg Drills (Chicago ets t Pneumatic Tool Company) were used and performed satisfactorily under the specific, _gonditions. The compressed air supply was affected by the cold environment.. Air entering the... _ subsurface pressure lines deposited ice which occupied as much as three-fourths of the [ pipes' cross section along the entire length of the line. The procedure suggested by Weber (1959) involving an antifreeze spray into the pipeline was impractical, since the diluted solution accumulated in the lower parts of the pipe and refroze. The most eco- < nomical, although radical, solution was to remove the complete pipe system and melt “|. the ice out, then re-install the pipes. It was found that six men could finish such a job ‘. in one shift. Under similar conditions, the de-icing procedure should be repeated every 3 to 4 weeks. TUNNELING IN PERMAFROST,REPORT II 5 \ a { a 7.5" a a e a RU PSS ER BL WSN ASA = . Figure 3. Drill pattern and shot round. , . E Solid circles represent charged holes. Open circle is the uncharged relief hole. Numbers indicate the order of firing. a Complete power needs, including subsurface operations as well as surface main- - enance, were satisfied by 35 to 40 kw-of a-c current and 300 ft? /min of air pressurized © 100 psi. : b 3lasting and explosives Types of explosives: Nine types of explosives were used in the tunnel during the 1960 season. Normal production would not require such a variety, but it was necessary . L | ‘o find the most suitable explosive for permafrost. Explosives used may be divided , i roughly into three groups: (a) high strength and velocity; (b) medium strength and velocity, ane (c) low strength and velocity. E Group (a) included 100% gelatin (Hercules) and malleable Military Demolition Block 5-4 (26,379 ft/sec). Group (b) consisted of a variety of explosives including 65% gelatin [Gelamite 1-X, Hercules), gelatin extra 60%, nitroglycerin 60% (Hercomite), and the Military Explosive M-1. Group (c) was also of great variety including nitroglycerin 50%, gelatin extra 30%, and a 40% gelatin (Dupont). This division was for the experimenter's use and is not meant to be proposed as a standard classification. Jy Drill pattern. The best drill pattern for advancing in permafrost is a burn cut ; pattern aritted To two-thirds of the width of the tunnel. The usual fire round shown in Figure 3 is applicable only for normal half-second delay caps. The use of millisecond ' i delays produced irregular fragmentation and the muck was scattered, since the material ' liberated by the first blast was, pushed down the drifts by subsequent explosions while r still in the air. : Ht tate e ee nee vee be Stemming. Under identical circumstances, stemming becomes a deciding factor in | the rational use of explosives. Table Ia shows results for the conventional method of stemming using clay to fill about one-third of the hole. A cold environment such as the i Tuto permafrost tunne). (-10 to -13C) presents an excellent opportunity to use another | method: mud, wet-tamped, was found to freeze solidly inthe drill hole. By experi- menting, it was found that a mixture of silt and clay freezes better and locks the’ hole | tighter than conventional clay tamping, which always remains plastic and only serves to plug the drill hole. The favorable powder ratio which was reached near the end of the season is attributed to the refreezing of the stemming. Results for typical cuses ! i ere given in Table Ib. TUNNELING IN PERMAFROST, REPORT Il Table I. Powder ratio, blasting of permafrost, 1960 field season. Amount of Type of explosive Date explosive in round (1b) Conventional stemming 10 Jun 100% pela- tin 2 Jun 65% gelatin 3 Jun 65% yvelatin 26 Jun 65% yelatin 6 Jun 65% gelatin. -?9 Jun 65% gelatin ‘et Jun 60% nitro- glycerin 5 Jun 60% nitro- glycerin ?4 Jun 60% nitro- glycerin b. Frozen stemming 3 Jul M-1 med vel 15 Jul 100% gela- tin -? Jul 100% gela- tin » ? Jul 100% yela- tin 20 Jul 100% gela- tin ev Jul M-1 med - vad Jul Mel med vel 77 Jul M-1l-med-.- - vel 28 Jul M-1 med vel ' Aug M-1l med vel 70 60 120 63 35 50 126 139 66 34 “85 67 105 42 “32 36 32~ 31 30 ratio 5.6 6.9 17.5 9.6 9.2 4.7 5.9 7.3 3.0 4.4 3.9 ea ye 3.5 3.3 Powder‘ Pile , character Spread Compact Spread Spread Extreme-. ly compact Compact Spread Compact Compact Satisface tory Spread Spread Satisfac- tory Satisfac- tory Satisfac- tory Satisfac- tory Satisface | tory Satisfac- tory Satisface- tory Fragmen- tation* Satisface tory Satistuce tury . Poor Very poor Extremely poor Satisfac- tory Extreme- ly fine Satisface . tory Poor Poor Fine Fine Poor/fine Satisface tory Satisface tory Satisface tory Satisface tory Satisfac- tory . Satisface tory General remarks No stemming used ‘Regular stemming No stemming used Stemming w/ sandy clay Pile in contact-with face Clay stemming Poor fumes, decom- posed explosive Unskillful loading, ‘loose tamping Unskillful loading, loose tamping .- Heavy boulders, de-| layed blast, fumes Heavy boulders Heavy boulders 5 cu yd diabase boulder Tightly stemmed Tightly stemmed, some fumes Tightly stemmed. ' . Boulders Tightly" stermmed. ~~ Boulders : Tightly stemmed. Boulders Tightly stemmed. Boulders peece No fragments larger than | ft?. Poor: Fragments of } ft* or larger are noticed. Mucking presents difficulties. TUNNELING IN PERMAFROST,REPORT IL earch Table 1. Powder ratio, blasting of permafrost, 1960 field season. (Cont'd) Amount of Type of explosive in | Powder ‘Pile Fragmen- ‘Date = explosive round (lb) ratio, character tation General remarks 6Aug M-l med 27.5 s.1 Satisfac- Satisfac- Tightly stemmed. vel tory tory Boulders. ° Mel med 27.5 oe] Satisface Pour ~* Tightly stenmmed, vel fory Boulders, 10 Aug 40% dyna - 40 3.4 Satisfac- Mediuin Tightly stemmed, mite : tory . Boulders. 17 Aug.3t0% dyna - 48 3.3 Satisfac- Medium Tightly stemmed, “mite : ; tory : Boulders. Results of observations. The explosives were used under a variety of stemming and priming conditions and different depths of implacement. In addition to the usual safety and stability demands, the nature of the environment imposed the following requirements: *(1) medium and low velocities were nceded for fragmentation and heave of permafrost, which seemed tough and elastic at the same time; (2) strength was considered of prima- ry importance since the matcrial was of high density and contained large boulders which prevented cratering; (3) insensitivity to frost was required, both in primed and/or residual state, and (4) insensitivity to pressure was required, since stemming and freezing back in the hole could produce considerable pressure on the charge if it contained excess moisture. It was found that high-velocity explosives were excellent in their shattering action and were ideal for fracturing large single boulders. However, their overall performance was inferior because of their very limited heaving action. Besides this, the Military C-4 became so insensitive that it could only be ignited with very heavy booster charges of nitroglycerin dynamite. . Low-strength, low-velocity explosives required large diameter holes and cartridges er simultaneous detonation, since a normal drill pattern would contain such long charges that they would cut each other off during a sequential blast. In contrast to Anderson's (1956) recommendations, experiments Gemonstrated that medium-velocity, medium-strength explosives produced the most satisfactory results. Table Isshows the results of powder ratio investigations for typical cases at vari- ous stages of work. Both parts of the table contain experimental rounds of the same drill pattern. Rock: conditions and overburden pressure are comparable. The same normal delay pattern was used. The powder ratio is the ratio of the amount of powder used to the amount of rock disintegrated and is a highly variable factor. It is influenced by the particular set of conditions, such as lithology,.type of work, etc. Itis also affected by the position of the charge in the hole, manner, of priming, stemming, etc. In addition, the low temper- ature and high apparent elasticity of permafrost, iv€., its resistance to very short dura-"~ tion shock, decrease the efficiency of the explosion. Brisance is a property of only moderate value, since any force applied to disintegrate a heterogeneous solid should be applied to its weaker portion, the ice bond, rather than to crushing the solid boulders. “Despite the fact that high-velocity explosives produce a narrower cone, minimizing the danger of cutting off adjacent unexploded charges, their overall action is rather poor, since most of the energy is absorbed by shattering of boulders. : By using medium-velocity, medium-strength explosives and frozen stemming, the powder ratio could be brought to a minimum value of 3.1 1b/yd? of permafrost (Table I). i Te 8 TUNNELING IN PERMAFROST, REPORT U0 Y VIENNA ING t= r- Ay Susy i x ASD UNS aN LAER SISA a. before blast. b. aster blast. Figure 4. Longitudinal cross section of the tunnel face. Note overbreak on the floor. This inay be lowered still more by applying millisecond delays and refining the drilling pattern. : . : There are indications that initial shots in the round cut off parts of explosive charges in the subsequent holes. This may be one explanation of the high powder con~- sumption during the 1959 operation, and at the beginning of the 1960 season. Two experimental rounds were fired with high-strength, high-velocity explosives in the burn (ceritral holes), and medium-velocity powders in the remainder of the drill holes (Fig. 3; #4,)). Despite some excessive spread of the muck pile, satisfactory resulrs were obtained. The data summarized in Table I indicate some success in the improved application ) of explosives. Despite the fact that explosives represent the cheapest source of energy, excessive,use of them would present a problem in excavation costs, especially under arctic conditions where transportation expense may become prohibitive. In addition, the increased drilling time would impose great expenses. | Ventilation and air flow The natural air flow in the tunnel during the summer is fairly simple to demonstrate (Fig. 5a); warmer outside air enters the tunnel through the portal and moves slowly inward depositing hoarfrost on the walls. Dry, cold, dense air moves out along the ‘floor of the tunnel forming a layer only 1.5 ft high. The layer is easily recognizable by the absence of hoarfrost on the lower part of the tunnel. wall... . An explosion at the end of the tunnel instantly liberates a large arnount of hot fumes and offsets the natural circulation, forming dangerous stagnant fume pockets (Fig. 5b). _ Forced ventilation applied at two points to act parallel with natural convection currents was most effective in eliminating them (Fig. 5c). With this arrangement, ventilation time was cut ‘down to 15 min, as compared with as long as 65 min using reversed fans. The effective fan capacity was estimated at 1000 ft} /min in both directions. This figure is based on one 7.5 hp exhaust fan, 3500 ft/min, at 4 in. water pressure differ- ential, connected with a flexible canvas ventilation pipe 24 in. in diam and a 3.5 hp fan of correspondingly lower capacity ona rigid ventilation pipe carrying fresh air in, TUNNELING IN PERMAFROST, REPORT I : 9 7 1e MOOtO Gb tebe to! : WM11 14 , ‘ a : b. GAS FLOW AFTER BLAST. (NO VENTILATION) fr . : SO FEET FRESH AIR aed INTAKE = “Yiyptpty “ptf te wy ttt ttt lied AGL “tz PUL UP LLEl Lille —_—[—$——> ? _—. 7 : GAS FREE aT on" GAS EXHAUST as! Ur -" “ >. ——— Saal “Eom eo OOOO OI 00 Uh 1 Vt WA Abt led: SF Vt C4 c. RECOMMENDED VENTILATION SET-UP Figure 5. Air circulation patterns. (The diffefente between the estimated and the nominal fan capacity was due to the ewbnormally high line loss along the 350 it, duc to hoarfrost forming in the line.) Miscellaneous uses of ircezing In the usuel mining procedure, there is always some cifort needed to lay rails and switches on a flat stable bed. Additional work for maintenance of the rail system is always required. A permanently frozen environment reduces that to a minimum. Rail- work laid out.on a flat bed of comparatively fine material becomes permanently bonded to the bed and is very stable if some moisture is added after the layout is completed. The need for ties is minimized and maintenance is reduced to a negligible amount. It : appears that the useful life of rail systems in permafrost environments is very long. .-- Similar-uses of the freezing environment were made in many cases where backfill was needed to prop up equipment, make foundations fur machines, ete” TO * DESCRIPTION OF THE TUNNEL _The result of the two seasons of excavating is a 605 ft tunnel with three roums exca- vated off the main drift (Fig. 6)*. The first room, approximately 10 x 10 x 12 ft, is on the left at the end of a 10 ft long adit 295 ft from the portal, and is separated from the main tunnel with a double bulkhead. The room will be used for long-range observations of the properties of permafrost. It is equipped with two mutually perpendicular semi- profiles of thermocouples and power units which provide a heat source. (Results will be published in a separate report.) or 29 work. sec oO). weber eae 12 TUNNELING IN PERMAFROST,REPORT Il Figure 7. Furniture and seismograph ‘foundation made from permacrete. Figure 8. Permacrete column sup- porting loose slab in the roof. Note also hoarfrost formation. Purma- frost tunnel, turnout to side room at 290 ft. by the surface produced a thin skin of frozen silt which is much more resistant and more efficient in binding loose rocks in the roof than is clean ice. Some skill was needed in the application of warm water. Repeated application in one area resulted in dangerous, although temporary, weakening of the surface because of the rapid addition of heat. The method of application — spraying or coating with a mixture — was unimportant. The result — a firm sxin on the wall and roof holding any previously loose material in place — wes quite spectacular. Roof strength was studied also by setting off charges of dynamite on the floor and observing the slabbing cffect. A tunnel segment of a given length was selected and every protruding boulder was marked with spray paint. Then a 2-lb charge of 60% dyna- mite was set off on the floor (6 ft under the roof), The experiment was performed with both a 6 ft anda 10 ft span. The shock invariably knocked out rocks from untreated sections, but failed to affect roof segments coated with a thin layer of ice or clay and rock flour slurry. wt % Another direct.mining application of permacrete was roof support by permacrete columns of large slabs which had become dangerously “drummy™. In one case, a9 ft” column made of four pre-cast elements was utilized (Fig. 8). One worker installed such a column in 6 hr including filling the molds (freezing time not included). . The column arrested the exfoliation of the roof. The unsafe part of the roof came to equilibrium and, despite repeated blasting in the vicinity, both column and roof were stable. Figure 9. Masonry permacrete Figure 10. Loaded pre-cast perma- arch, 560 ft from portal. crete arch, 620 ft from portal. Floors. To obtain flat usable floors, an extremely simple method was successfully employed. A 6-in. layer of fine -crushed rock (pea gravel) was spread, filling depres- sions and irregularities in the natural permafrost floor. It was allowed to cool down to -5C.. A mixture of water and snow was then poured over it. After solidification, this floor withstood 250'psi rolling wheel load. It was especially resistant, even to sharp blows from picks or sledge hammers and any damage could be very easily repaired with sand and water. Moisture content was held at approximately 35% of saturation value. The-rough texture oi the floor surface was found to be advantageous, and no attempt was mece to epply a smooth finish. NT : 7 - Bricks and arches. Masonry work, such as laying permacrete brick, was tried in the tunnel. It wes concluded that masonry with permacrete does not differ much from its ''warm'' counterpart. However, it was found that the solidification time for small pieces of permacrete is much shorter than for small pieces of concrete (3 yd} froze in 30 hr). - > Two types of permacrete arches, masonry (Fig. 9) and pre-cast (Fig. 10), were erected for investigation of: (1) applicability; (2) labor involved; and (3) creep investi- gation. , ‘ ~The ‘conclusion from this investigation is that permacrete arches are practical in this environment and that the actual amount of labor required in making them is less" - 77" than is necessary in concrete work. 1 ‘ Beam experiments. Since it is suspected that an unfavorable arnount of creep exists i in permacrete beams, three long-range tests have been set up (Fig. 1}). Two of the ' beams have @ cross-section of 10:°x 10 in., are simply supported, and have a span of 8 ft. The other is a cantilever with the same cross-section and an unsupported length of 8 ft. All three beams are subjected to dead load only. Deflection can be determined by comparing reference points at l-ft intervals to an independent straight line. Prelimi- nary data show no unfavorable creep. | TUNNELING IN PERMAFROST,REPORT I ~ et ey’: “é . cS 8 alas bia a3 \ Figure 11. Permacrete. beam experiments. Table Il. Permacrete mixtures. (In all cases water-saturated) ‘| srain size Poured (mm) Mortar Brick Column Floor cast 20 - - 0.7 - - 10 - 0.6 - - - 5 - - - 1.0 0.2 1 “ 0.4 - - - O.1 0.4 (40 mesh) 0. 25 0.2 0.15 - 0.2 0.08 i (200 mesh) 0.1 0.2 0.15 0.5 { 0.01 oO.1 - - «= Clay 0.15 - t - - Final . . : porosity 20%. .. 22% 27% 40% 31% TUNNELING IN PERMAFROST,REPORT U 15 dptimum: composition Optimum mixtures for various purposcs were obtained by a scries of trials, The -esults are summarized in Table Il. The data in Table Il are mercly preliminary nformation. There is an obvious need to investigate the problem of optimum mixtures for any specific use of permacrete. However, some general principles may be stated. In the case of an aggregate of uniform spherical particles, the theoretically obtain- able maximum bulk density is 74.05% of the density of the particles. The addition of another size of sphere, just fitting into the pores, will increase maximum density to approximately 30%. Further introduction of successively smaller spherical particles will gradually decrease the pore space and increase the bulk density of the mixture. However, the greatest strength isnot necessarily related to maximum density. The addition of increasingly fine material causes a preater dispersion of water droplets, and thus the freezing temperature of the mixture is lowered. That means that a mixture containing a great amount of fine material would have os great amount of unfrozen water at a given temperature. Therefore, particles lp and smaller should be avoided in any mixture. - An aggregate of angular particles always has a wider range of void sizes than an aggregate of spheres. Therefore, mixtures of angular material require a more finely grated filter. The strength of a specimen seems to be affected also by the ratio of the size of the coarsest fraction to the cross ~section of the specimen, which determines the upper lirnit of the particle size. In addition to recommended compositions given in Table Il, the following set of general rules was established. 1. Complete saturation and especially supersaturation of the mixture produces weakening of the frozen material and increases brittleness (see Appendix A). A satur- ation (thawed) between 90 and 95% gives best results. 2. Compressive strength is highest when the coarse fraction is high. The com- , position of the pore filler is irrelevant. 3. Greatest tensile strength is obtained when the finest fraction is smaller than 0.01 mm and the ratio of coarsest to finest is low (exact values of that ratio have not yet been determined). There is a definite need for further investigations which are presently underway. Tunneling in cold permafrost is very similar to operations in competent rock in temperate climate. The disadvantages, such as the need for entifreeze solutions and for fully winterized equipment together with other smaller disadvantages, are offset by the greater eificiency of explosives and the ease of use of artificial frozen soil material as an aid in mining.: : The best method for tunneling in permafrost is a cyclic system consisting of mucking, drilling, blasting, and ventilating. The best drill pattern is a burn cut pattern drilled to two-thirds the width of the tunnel. Medium-strength, medium evelocity explosives with a delayed blast and a 0.5 sec interval are recommended: Nothing can be said about millisecond delay caps,. pending further investigation. Charging the burn (central holes) with higher velocity explosives provides advantages, since the material in the face shattered by the sharp impact of the burn is removed and placed in a compact pile with a good fragmentation. 3 The best stemming is a wet clay-silt mixture which fills the drill holes fully and is ‘allowed to freeze back completely, sealing the entire hole. The cost of mining in permafrost is not higher than in mining warm rock. An estimate of the cost for the 1960 operation is given below: . 16 TUNNELING IN PERMAFROST, REPORT IL Contract personnel wages (5 persons) $15,000.00 Army personnel (9 at $300.00/ month) 8,100.00 Camp costs (14 men at $5.00/day) 6, 300.00 ; Amortization (1/5 $60, 000. 00) 12,000.00 Explosives : 2,200.00 Fuel . 800.00 t $44, 400.00 ‘ Estjmating that the work done in 1960 is equivalent to 620 ft, the cost of 1 linear ft is * $71.16 tor a 6 x7 cross-section, of, considering that the tetal volume of material ree + aneved was 1000 yd, the cost of removal was $44.40/yd'. A comparable tunnel in the Yo continental United States would cost approximately $S5.00/tinear tt. Most of the lower * Gost is due to lower labor costs. Itis apparent that i the tuners were pad an wverage U. S. hourly pay, permafrost mining costs would be only slightly lower, Itas emphasized that maximum productivity per manor machine could be ine reased further, Mucking could be as high as 50 cars/day (LO-hr slnit) tor a crewoat five (avere age Was 27 cars/ shift), Drilling (one drill, two men, 10 hr) could exceed 220 tt, but average productivity was around 150 ft. The above maxima would be applicable in mine ing in permafrost where stagyered stages of production could be applied successfully.- Subsurface shelters, storage areas, and military installations could be excavated in permafrost with certain advantages over warm rock. Beside the advantage of low temperature for storage, there is the ease of construction of foundations, partitions, etc. Freezing temperatures can be used in a variety of subsurface jobs, suchas laying rails, stabilizing walls and roofs, shoring up ceilings, and repairing fractured pillars. Perma- frost resistance to explosions is similar to that of competent rock and it does not deform with time as do snow and ice. Permafrost, and permacrete, can withstand flash heating such as occurs during black powder explosions or rocket firings. It has been demonstrated that permacrete may be successiully used as a substitute for concrete in many fields of construction. Small-scale construction is most success = ul for any such subsurface work in permafrost where preservation of culd is anticipated. There is not much difference between manufacturing pre-cast permacrete and pre-cast concrete. The difference is that permacrete does not require portland cement. Perma- crete has a comparatively short "curing time’, freezing time only, and can be remolded * and reused at any time. Labor and machinery are utilized in the same way as in concrete work. ° , The use of permacrete in tunneling in permafrost is most advantageous when it is applied to roof and wall support by spraying and plastering with unfrozen material. | Utility, rooms, research laboratories, and storage rooms could be constructed by plaster- ing rough excavations in permafrost with a saturated mixture of relatively fine material. Permacrete may be used at the surface, as well as underground for foundations and forti- | fications in permafrost regions. In summer, permafrost tunnels can be ventilated withour refrigeration only in cold permafrost. Permafrost whose temperature is close to the melting point would need refrigerated air for ventilation unless operations are limited to the winter season. RECOMMENDATIONS Since tunneling has proven to be possible and feasible for military installations in cold permafrost, it should be’investigated for warm permafrost (only a few degrees “below freezing) in a région such as Alaska or northern Canada. : Observations of long spans in permafrost should be continued. Natural arching and . roof failures should be produced and measured. : : = Investigation of permacrete should be continued in the laboratory and in the field, based upon the knowledge already gained in concrete research. Temperature investigations in the tunnel may reveal] data on thermal history from the start of the present geological period until the present time. It is recommended that thermal observations be continued and correlated to glaciological data. ‘" ‘ ' ee TUNNELING IN PERMAFROST, REPORT I 17 A small camp should be erected in the large room in the tunnel to demonstrate its feasibility as a shelter. : f ‘ f REFERENCES Abel, J. Fo, Jr. (1960) Permafrost tunnel, Camp TUTO, Greenland, U. S. Army Snow Ice and Permafrost Research Establishment, Corps of Engineers, Technical Hs Report 74, L9p. ; FY : : Andersen, L. G. and Moyer, P. R. (1956) Blasting in surface and drift operations in the far north, in: The dynamic north, Tech. Asst. to Chief o tur Polar Projects, » Chap. 4, p. led. Nuval Ope rations a q Arctic Construction and Frost Effects Laboratory, (1936) Determination of errors in temperature measuring equipment, first interim report, Corps ot Engineers, U.S. Army, Miscellancous Paper 19, . Bakakin, V. P. (1958) Osnovy tedeniia vornykh rabot v usloviiakh vechnoi merzlotv (Principles of mining in permatrost). Muscow: Gosud. N.-T. Izdat. Literatury po Chernoi i TSvetnoi Metallurgii, 23lp. (1959a) “Osobennosti gornogo dela v oblasti rasprostraneniia merzlykh porod i glubokogo zimnego promerzaniia (Characteristics of mining in permafrost areas and areas with deep winter freezing),"" in: Material po inzhenernomu merzlotovedeniiu, Institut Merzlotovedeniia, Akademiia Nauk SSSR (Moscow), p. 129-130. = (1959b) “Osobennosti proizvodstva gornykh rabot v moshchnoi tolshche. merzlykh porod (Features-of mining in deeply frozen ground),"" in: Osnovy — geokriologii (merzlotovedeniia), Inst. Merzlotovedeniia, Akademiia Nauk SSSR -(Moscow) Pt. 2, Chap. 7, p. 219-230.. (1959c) "“Usloviia stroitel'stva i ekspluatatsii gornykh perdpriiatii v Pechnorskom ugol'nom basseine (Mine construction and exploitation in the Pechora coal basin),"' in: Trudy soveshchaniia po ratsional'nym sposobam fundamento- _stroeniia na vechnomerzlykh gruntakh, Vorkuta 1957, Moscow: Gosstroiizdat, p. 47-55. . . + etal. (1958) Prokhodka i ekspluatatsiia shakhtnykh stvolov v Pechorskom ugol'nom basseine (Excavation and exploitation of mine shafts in the Pechora coal oar Materialy k Osnovam Ucheniia o Merzlykh Zonakh Zemnoi Kory, vol. 1, p. 195-215. i .Blinskii, A. I. (1946) Podzemnaia razrabotka ugol'nvkh i rudnykh mestorozhdenii v oblasti vechnoi merzloty sposobom zzaxledki l’'dom vyrabotannykh postranstv (Minin or coal end ores in permairost regions by blocxing workec-out spaces with ice), , ; 7 i Merzlotovedenie, vol. 1, p. 131-135. Bratsev, L. A. (1945) “Shakhtnoe stroitelstvo v usloviiakh vechnoi merzloty Vorkutskoge kamennougolnogo basseina (Mine shaft construction under permafrost conditions of the Vorkuta coal basin), "' in: Reports on 1944 Scientific Research, Otdelenie : ij _, gpeologo -geograficheskikh nauk, Akad. Nauk, p. 120. (Abstract). | Chekotillo, A. M. (1945) Primenenie snega, 1'da imerzlykh gruntov v stroite]' nykh tseliakh (The use of snow, ice and frozen ground in construction). Izdatel'stvo Akademii Nauk SSSR, 3p. i . Kamenskii, G. N. (1947) "“Gornye raboty v usloviiakh vechnoi merzloty (Mining under permafrost conditions),"" in: Poiski i razvedka podzemnykh vod. Moscow-Lenin- grad: Gosgeolizdat, p. 281-283. epg ss APPENDIX A. 4. A thin plaster-like paste of silt (rock flour), clay, and water was troweled on e surface and allowed to freeze to the permafrost. (A very time-consuming ecess). Test no. Diam (mm) ‘Test no. Diam (mm) 1 3. ts 3. 2 2.5 *8 2.5 3 re 2 4 2.5 2.5 5 3. ‘6 3. 7 Ave 2.65 Remarks: Every test showed clean, conical holes, only very litthe peripheral acturing. roclusion Coating of the tunne] surface witha clayey water solution improves the skin condition id reduces the danger of rock fall, Addition of clay and rock flour to water improves sin hardness. 1 ‘theness of permacrete It was noticed on several occasions that some permacrete mixtures displayed an ta+asirable amount of brittleness. The following test was devised to formulate ideas as » .e influence of composition on the brittleness of the permacrete. The material was cast into blocks 10 x 10 x 30 in. and dropped lengthwise onto a tine rail. The height of drop was increased until damage occurred. The maximum : tht of' drop at which failure occurred was considered the reciprocal relative brittle - f Be Composition 1.- Till, remolded Saturated . Supersaturated 2. Pea gravel Saturated 60% of saturation 3. 50% pea gravel 30% silt Saturated Supersaturated 4. Varved clay from shear moraine 40% moisture content (Specimen bends!) 3. 40% pea gravel -° 30% silt 20% 1 in. pebble 10% clay a Saturated 6. Poured clay 70% moisture (ice lenses) 7. 20% pea gravel 20% 1 in. pebble 30% rock flour : 20% sand 4 10% clay a 20% moisture sed Saturated « = 10% moisture Bae Height of failure (ft) mw ow 6 and more i Er ll I 2 2.6 3.9 2.4 APPENDIX A. A3 - tSonclusion Clay as an additive decreased brittleness, but a predominance of clay in the mixture produces a considerable increase in plasticity in the frozen state. The best mixtures seem to be heterogeneous in size with only 10% clay. The mixture should ever exceed saturation. en ca a ee ee ee YO re - an? woe i. en axe 4G -—— ta. APPENDIX B Manufacturers' Literature pecification xe ! intheader (STANDARD; WITH MK IIA ENGINES IVERALL DIMENSIONS te, . igth 5 740 mm (18'-10") * ght - 1 280 mm (4°—2%"") Vidrh — maximum 1715 mm (5'—7'5"') . ‘ath = minimum (without bollards) : 1475 mm * (4°~10") “OTAL WEIGHT OF MACHINE 16 750 kg (16.5 tons) TTING SSSEMBLY DOsco tt Suit Customers recuirements 917mm : 135.18") 0.75 - 1.82 m/s 1148-385 4min.) 1.27 — 3.05 ms 1250-600 ft/min.) RCE AVAILABLE AT CUTTING HEAD 2ifting . 200 kN rex. (20 tens f. max.) \“-x, Chain Pull VIZ KN © 1.27 mis (11.7 tons f. © 250 ft'min.) i omping thrust avelladie et cumiing head 90 kN © 70 bar {9 tons at 1 000 Ibf.in? ) Type of comer picks — .Ditferent tyoes availsbie, Recommencations depend upon strata type) ADING ASSEMBLY Fyde of Conveyor ; Scraper » ss Sect‘one! Aree 0.123 m? (1.32 sq.ft.) ted of scraper {normal) C.84 m’s (165 #.'‘min.) Speed’ of sereper ‘with cross conveyor) 1.07 mis {210 fr'min.) \ x. ‘Sading vol essuming full trough (normal) 372 mich i586 cu. yds‘hr.) ‘om. ‘Sading vo: assuming full trough , with cross convey Or) 470 mi vb (615 cu. yds-‘hr.) Tig SF ceivered te motor ICS kW (14 hp) ector Gust de enstied for 'oose eter.al leo. 0.66 2.0. Coal, 1.5 for Gypsum). AWLER ASSEMBLY .. Luteils of chain — 56 finks at pitch of 23 =m {3%"") ensth of track on fioor . 1 473 mm (4°-10") ' ath of track 456 mm (14") | Dung Pressure a 0.145 Mivim? (21.6 tof/in? ) Track Centres 6 ‘ ae - 940.mm...0 = vee (3% 1%) as | ged — working - 0 - 0.03 m‘s (O—6% ft/min. ‘- ced — maximum tramiming 0.98-0.10 or 0.14 m/s {16-19 or 28 min.) Type of mctor — Hydrestetic Transmissions 9 kw {32 hp) YDRAULIC EQUIPMENT . umber of pumps ots! capacity of Dumps umber of hydraulic motors it capacity forking pressures of conveyors ‘ecommendec hydraulic fluid ‘LECTRICAL EQUIPMENT dydreutic pump motor ‘water cooled) "ore! electrics’ Dower foreae © "recuency Sontroi Panel Dil ieve! switch Traiiing cable deadiema ii per m’c) Pump mote: cable Ligttine and ditot cadle Hycreuiic oi! thermostat WATER CIRCUIT (Stangard) Sete of ‘iow: - Working pressure (2 tandem 3.6 Is iS8 calls‘min.) ¢% including conveyor and track motors 364 litres {BO galls.) 440 bar (2 000 lbf-in= ) Aquacent ‘Light’ or ‘Heavy’ F.R.F.s or Welkers P.W.L.C. minera! oil? 90 KW . (720 h.p.) 90 kW (120 h.p.) 550-1100 V or 405.440 V 50 or 60 Hz - Balcewin & Frercis or to suit customer Mobrey Maonetic type Type 7 — SC mm= (4 Pilot} (1 Earth) (2 Power Cores) Westair Dynamics 24V. 70W. or 19 suit cust¢mer Type 7 — 50 mm? Type 62 — 4 mm* Mactaren or Samford Type 2°85°C. (25.185* F.) 0.26 — 0.38 I's (2%=5 galls ’min.) 42 bar (1.80 Ibfein* } ISSUE 1/79 \ Ointheader Bilal clei Main Conveyor A Three Heading System. ! Supearts 1 te MaNetors f Tuma 4 bene. 2a Lee cutting sn Short Right-Angled Conveyor —— Surcoris Main Conveyor Bridge Conveyor Mono-Rail Supported Ointheader alin 6753.E. 47th ave. Dr. Suite H THE DOSCO CORPORATION _ Cemer Colorado 80216 Western Division 303-321-5597 Telex 45-4369 DON : ups t September, 9th, 1981. Ma. David Krebs, Senior Paojfect Cuginecr, ERTEC Rocky Mountain, 1746 Cote Bevd., Golden, Co. 80401. Dean Mr. Krebs, In response to our phone conversation of this morning, 1 am enclosing information on, the Dosco Dintheader for the Alaskan Coak project you are studying. The Dintheader'is a small, simple, yet very robust machine capable of cutting rock up to 10,000 p.4.4. and coal at a rate of up to 4 TPN. The Dintheader would be an excellent took on this job because of its simple design, 14 tons, one 145 H.P. motor to aun the hydraulic system which runs the cutter jib, conveyor, and tram, and that i4 just about it. Dust collection hoods are Sige for the Dinter 4§ required, however nonety an exhaust fan and tube 4 used. The cost of a Dintheader, F.0.B. U.K. port for the end of 1981, approximately $446,000. However, there are two units available within the States at a much Lower coast. ’ 1 am abso enclosing brochures on our other equipment for your information and if I can be of any further assistance please cate at any time. Best regards, fee SN DAVID M.° NETL Manager (Western Division] ENCLOSURES A HAWKER SIDDELEY COMPANY [AM-5- [PDX LRB-154 ROOF BOLTER WOR om a EZOSRE Bist oN YOU CAN SET MORE ‘BOLTS WITH Tals MACHINE 1. Maneuverability .... Get in, fast; get out, fast! 2. Thrust... . 2. eee eh ake ne he Ns ree so el Vee eer Ems . . and produced the model LRB-15A Roof Bolter which has no peer for roof drilling and setting root bolts in underground mines. Rewer: BIW Bulletin 6-475-1 rm ee Bless Deer ua LONG-AIRDOX BITS AND RODS... veda. - « » MEAN FASTER ROOF DRILLING ee aS ot 3 TET OF ee ee Se oe Give your ropf bolter the benefit of smoother drilling with Long-Airdex bits and rods, contoured for fast, smooth drilling and collection of cuttings, and engineered to match the per- formance of Long-Airdox roof bo'ters. vide the uncbstructed flow of cuttings. CEST STE: Leng-Airdsx bits are produced by carbide tool specialists for - fastest penetration, longest wear and effective dust collection. & : 3 The rods support the bits with the strength required to ‘ransmit FE the thrust and torque for unmatched penetration . . : E F i . and pro- f 6 P E E F ik i Conveniently Located to Provide Maximum Service to Our Customers Benton, Illinois 62812 Box 479 {612) 438-3821 St. Clairsville, Ohio 42950 Box 1 (614) 695-1790 Finleyville, Pennsylvania 15332 R.D. =2 (412) 348-7143 ; | BIW Bulletin 6-475-1 f ; ] Robinson Creek, Kentucky 41560 {606) 639-4493 Lo... Sea oe Ce ee | Camden-on-Gauley, West Virginia 26208 ' (304: 226-3571 er f , eae : Rarper, West Virginia 25851 (304) 2$3-4812 | Price, Utah 84501 | (801) 637-3236 : LONG-AIRDOX Co. a division of THE MARMON GROUP, Inc. Bex 331, Cak Hill, West Virginie 25901 ECIALISTS IN UNDERGROUND MINING, HAULAGE, VENTILATION SYSTEMS — Th are SO INE Vehicle” lesel RAM GAR® REY | EE Ee aaa er ee ELT EEL SE EY NO PPL ESET BK Sac SA P ‘ k juilt to MSHA requirements for underground coal/hard rock mining ‘ 1 44 ton (12.71) teted capacity for coai; 18 ton HB 9C galicn (341 liter} water tank sufficient for two (16.3 {) maximum Iced limit full snitts of exhaust scrubsing t ales | B Dirt locked out of 43 gallon (162 ‘iiter) 5: iz- 17° to 21" (432 mm to 533 mm} ground ciearance Niceta ees era : ed hydraulic reservoir for bac bottoms Yu : ; : ; : ___ EE Noise ievel reduced by fuily enclesec engine é-wheel chain drive permits ire tracking. elimi- companment nates axie-mounted gearing and differential : : t buige K Designed for tight turns: inside circie radius i E a ; 10°9" (3.28 m), outside 223” (6.78 m) Cantilevered canopy provides swing-away , : access to sSound-insuisted operator compart. B Fiat, seziec tractor Dottie. keeps dirt and mud 4 ment. improves visibility cut of engine compariment ft Axia! osciliation pivot keeps all four wheels on EH B-hour changeout Schedule 31 (Title 30, Part 36) the ground in turns from steep grades to level Diese: Power Pack ee Tee Overall height (A) ...-..-----..--:--cceceeeeeeseeeececeeeeee 26" 28%" 30%" 32%" Ground clearance (B) 2.2... eeeeeeeeeeeeceeeeceeetee 5%" 85 10” hee ~ Drill head height (C): a I On level ground oo ececccccesccceceesceeceesectieeeeeee 10" 1214" 1404" 16%" : Minimum ceccccccccccleseeeeeeeeeneeeeee 10" 12%" 14%" 16%" |! WAST <cidnceveee cones} svonteeersnseeereeecnree TO" 72¥2" 74.4" 76%" E Drill Boom Tif ee ceeecceeeseseeeeeseceeee ceteenaneeereeeee 520" 5-0" 5'-0" 5.0" y Overall length osc ccccccccccccecc cece srveitemencensceeee TAUGVE"™ 14.9%" 149A 14.910" Overall Width ooeeccccccseeseeeese ceetete ee lesseeemansnseeee 60" 6'-0" 6'-0" 6'-0" ; Five Stxe <ccsecssssoscsssssesstinsenseseeseserceenes ermeiene 7OO.KI2 7.00 x12 “700x112 7.00% 12 | Wheelbase <2 (52 2c. oct Picco cee let ‘-6" ‘-6" ‘.6' B Drilling: Speed on. scencnee cence cesceeceeeeeeeee sees: variable, C to 550 rpm Torque: an See ceee se variable, 0 to 247 ft. Ibs. Drill boom: LIF eee eect ceeeeteeeceeeseecteeeeereee HYOraulic Stabilizer en eeeepeeeeeeeseeeeeeeeee hySrautic, centerpoint Thrust smc. nnnee up te B900= — at 2000 psi Speed (feed) -W.....--.------------- --- UP 16 27 fpm Tramming:. . TY Pe -.--nennnnneeeeeeeee eesesnenes hydraulic, 4 wheel SOROD sna nenneccnnncnnnncevseesnvemenensne ance variable, 0 to 2% mph teering qececceeeseeesessecesecseseeseeee CrAWiIEr Style, rotates ebout its own ceriter of gravity (otal 10) | ee hydreulic, push pull, spool valve FEATURES OF THE LRB-15A ROOF BOLTER Panic bar: power from etectric motor anc brakes are set. lever operated panic bar removes Electric motor (1): AC (1800 rpm, continuous) .. 40 hp DC (1806 rpm, continuous) .. _.. 20 hp Trailing cable recommendation: AC neeeeensenceneecceceeeceneceeeeeeeeeceeees 3 cond. =6 . type GGC round secseceeeeeee 3 CONG, =H type W round OE Dust coliesor -.u. ee Througn-The-steel, cyclone end filter - bag collector Hydraulic oil tank 2 ee 55 gals. _ Brakes... eee eee eee “dead-man” type, . spring set, hydraulic release Cable reel 2. nnnnnenee eee horizontal axis, hydraulic Weight of machine -.......-.----.--.------- 7500 Ibs. Permissibility: MESA approval of the etectrical __system, the dust contro! system, sefety fea- tures, etc. Fire suppression system (one canister, dry type). Rigid canopy for operators compartment. Hydraulic power take-off (for operating hydrau- lic tools, ete.). Hydraulic clutch to disengage dust collector vacuum pump when tramming, etc. Hydraulic canopy to protect operator at drilling position. C spe Overs" Aegan SN Over S2n0Py . SPECIFICATIONS: ea 4aii4 Diesel RAMCAR' Haulage Vehicle on moo Optionat Optiona! bruceizies St ering. TOL ae CES tank O° e538" WEIE” LENA g gone “rersmussion NOTE: We reserve the "isnt tc change sr ie this 5 previous! cetors erpearags eno incurring ery poeeion for ecuis Shs 1. JEFFREY MINING MACHINERY DIVISION ORESSER INDUSTRIES. INC. FO 50x 187. COLUMBUS. Oni 4521€ USA + Phone €24 257-3123 Se lee a a oe eet eee epi erie 41 sop ‘ : ao 1 Yceags cas ose seser WAYNE. fab oA eee W200 aa | SE es Wey Ce (get ie A 3.00 29]19) Wea 97 Poe ee a O14! aie ieee 0 Nive fo... “ o a8 SD Gk 4114 Specsiscaerions “yntrols - continued This is operated by the ériver's left hand and the main steering control Jever is operated with his right hand. The throttle and service brakes are‘operated by pedals which are arranged with the standard automobile layout. t Two simple mechanical interlocks sequence the following functions: 1. The engine can not be started unless the shift lever is in the neutral position. 2. The manual override of the automatic shut-down device can only be operated with the parking brake in the applied position. ; sin Frame “The main chassis is constructed in 1" thick plate with a 1/2" wrap around sper plate protecting the engine from a rib impact. Easily removable cover e-2tes keep the engine cozpsrtment clean. FE= Position —The lateral driving position situated between the wheels, together with the long wheeibase of the RAMCAR, provides operator comfort, convenience, and safety iich are unrivalled by any other haulage unit currently on the market. A heavy Laty molded seat with good back support is mounted on a hydraulically dexped load leveling suspension systex. 1 (_railer ® The trailer frame is Tuggedly constructed in high strength steel. RAMCARS ve been operating for over eight years, and so the general principle and mechanical ‘_-sign are well proven. vformance Low gear is designed to give the RAMCAR sufficient tractive effort to spin the wheels and provide a maximum speed of 2 mph. High gear gives the RAMCAR a ximum operating speed of 6 mph on level ground. A total hydraulic pump capacity ~- over 40 gpm ensures rapid unloading. tmensions and Weights Dniaden weight approximately , , 42,000 Lbs. Maximcum rated load... . 1. 1 ww ee ee ee ww we we ww ww © 28,000 Lbs. GV ose oS So os, oe cee + 6 0 0 6 0 os eee oe 8 & 6 37s FOSOUD IDES Cubic Capacity. . Struck Level». 2-1 ee ee ee ee ee ee 1 190 Fig 6" Sideboards ». « « 1 0 0 6 0 0 0 0 tw to cw 0 tt 6 oe 2a4 Fes 12) Sideboards © oe ee ee ee ee ee oe B82 Fed Mr giscteards 2 PL Pliiri tii eee Overall height (Frame). , fw ee ee ee ee ee we ww 59N/2" Trailer body height .......262+.+.+.2..40.4. (Struck Level). 43" DERGCOl Game: Go ee 5c: %0 26 Oi ehete ve nosne ne 6 on'e 20S 6. chee 16 « eee Preider SIOChe hres kok ko ahs SC aie soe) south e ometeuae cae edeee Overall Bength 62. 63h bees oe oe She ON Sete 6 ee ete « oe Saeed Turning Radius . . . . Outside a Oe te Me hes 10 eke: 6, ie He beERe 4 eluoe eee Tusiden sk Se 6. CREE Lr Turning Articulerion., <5 oleh ects, 0 0dnene ie) « 618) Sereiiel ss nade Meee Ground Clearance .-.%. ss 0c 6 3 00 0.0 0 6 oo 6788 © & 650 0 ehkOe Besgnr over Canopy, 2.6 5s. oie 0 eles) 6 eee be Sineneae oc Oe Opee ss seme owue - 58 - in Features of the Diesel RAMCAR Ro trailing cable Ro battery Long wheelbase Dise brakes on all wheels Bigh ground clearence and ramp angle ,; Tight turning circle (articulation) + Safe operator's location (between wheels) Fast (5 seconds) unloading Simple controls (no side mounted steering wheel) No chain conveyor or conveyor drive Ko complicated steering linkages Diesel engine placed: 1. For easy accessibility and maintenance 2. Remote from ore for cleanliness 3. Centrally located to protect it from rib damage 4. Eesy "Power Pack" change out Full time 4-wheel drive Comfort designed operator compartment Sinple hydraulics Good operator visibility “ wide, high flotation tires 2-Pest cantilever canopy 5/79 20 YEAR MINE pilin, MINE WASTE DISPOSAL PAD wollyye, ROAD TO WAINWRIGHT saw lh SS soil White =| al|— 19 | ala WAINWRIGHT COAL STUDY AREA A-B CONTOUR MAP CONTOUR INTERVAL - 25° PREPARED BY: L.D.M. JOB NO. 81-001 DRAWN BY :RD.C. SCALE : "= 500° CHECKED BY: DATE : 9-17-81 B-A2 -69 O 6.5C 20 YEAR MINE -\\0 ee eG “5 ei oe Say oo oe — ee ee ia projected ? SPLIT IN SEAM POSSIBLE SEGENO roa > conic -100 ELEVATION~ TOP OF LOWER COAL SEAM services CONTOUR INTERVAL : 5° a 6.07 COAL THICKNESS THICKNESS. INTERVAL : 0.5' 0 WAINWRIGHT COAL STUDY DRILL HOLE NOTE: LACK OF INTERCEPT DATA IN HOLES A-Al AND A-A2 MAKES IT IMPOSSIBLE AREA A-B LOWER SEAM TO DETERMINE THE EXTENT OF THE PARTING SEEN IN HOLE B-3. THE APPARENT SEAM THICKENING TO THE N. OR NW. MAY BE THE RESULT OF THE COALESCENCE OF THE SPLIT SEAM IN B-3, AND THE SPLIT MAY WELL BE PRESENT IN THE AREA OF A-2. PREPARED BY : L.D.M. JOB NO. 8I- 001 DRAWN BY: RD.C. SCALE : I"= 500! CHECKED BY: DATE : 9-17-81 MAP 4.2 Bol 23" 5 o.s' SCALE: HORIZONTAL 1"=500' VERTICAL 1'=50' 8 1 25 -50' 8! 3.0° -100' T.D. 127° | Lal {3 La Lee) services =I WAINWRIGHT COAL STUDY AREA A-B FENCE DIAGRAM ~ NORTH PREPARED BY; L.D.M. JOB NO. 81-001 DRAWN BY: P.D.C. SCALE : CHECKED BY: DATE: 9-18-81 4 : -1004 3.0° 150° HORIZONTAL 1''= 500° VERTICAL "= 50' SCALE : services Incorporated WAINWRIGHT COAL’ STUDY AREA A-B FENCE DIAGRAM - SOUTH PREPARED BY: L.D.M. JOB NO. 81-001 DRAWN BY: RD.C. SCALE: CHECKED BY: DATE: 9-I7-81 | MAP 4.4