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EXCAVATIONS

Geological factors

965343 Design of the jointed roof in stratified rock based on the voussoir beam mechanism P. Mottahed & J. Ran, CIM Bulletin, 88(994), 1995, pp 56- 62. Mining practice and research have shown that the jointed roof in stratified rock behaves like a voussoir beam structure with strength greater than that determined by the continuous beam theory. In this paper, mechanism of vonssoir beams containing multiple mid joints and truss support are studied and applications of the voussoir beam mechanism to under- ground mine openings are discussed based on the numerical and experimental results. (from Authors)

Stresses around openings

EXCAVATIONS:MINES & QUARRIES

965347 Problems of improving the quality of hydraulic tunnel finings and preventing their damage dm-ing operation V. M. Mostkov, Hydroteehnieal Construction, 29(2), 1995, pp 123-129; translated from: Gidrotekhnicheskoe Stroi- tel'stro, 2, 1995, pp 49-53. Regular inspections of tunnels, carried out in the past 20 years detected numerous defects and damages of linings, which led to increased susceptibility to landslides, loss of stability of the underground structure and creation of an emergency situation of the hydrostation. Some damage required immediate repair. The unsatisfactory state of tunnel linings and disturbance of their operation are manifested mainly: in excess seepage of water from the tunnel and damage to the lining surface and in the formation of large cracks in the linings and their destruction. (from Journal translation)

965344 A large strain analytical solution for cavity contraction in dilatant softs H. S. Yu & G. T. Houlsby, International Journal for Numerical & Analytical Methods in Geomechanics, 19(11), 1995, pp 793-811. An infinite dilatant elastic-plastic soil mass contains a single cylindrical or spherical cavity within which a slowly increasing pressure is applied. The removal of the cavity pressure takes place after a partly plastic state of the soil has been reached. Closed form solutions for the stress and displacement fields in the soil during any stage of the unloading process are derived. (from Authors)

965345 An artifical neural network for forecasting the amount of Chinese colliery roadway surrounding rock deformation Yuxiang Zhang & 6 others, in: Applications of computers and operations research in the minerals industries. Conference, Brisbane, 1995, ed ANON (AusIMM), 1995, pp 123-124. This paper puts forward an artificial neural network (ANN) for the forecast of deformation of the surrounding rock deformation. On the basis of this, this paper gives some examples of its application. The results show that the ANN model has a high forecast accuracy. (Authors)

Tunnels

965346 A geotechnical survey of phase 1A of the Lesotho High- lands water project F. G. Bell, P. J. H. De Graaf & D. R. Haskins, Quarterly Journal of Engineering Geology, 28(4), 1995, pp 317- 332. The Katse Dam and Transfer Tunnel are constructed in the basalts of the Drakensberg Formation. Many of these basalts have been subjected to deuteric alteration and consequently contain expansive clay minerals. Their presence can mean that the basalts disintegrate rapidly on exposure, which has led to increased excavation at the dam site, and slabbing and spelling from the perimeter of the tunnel. The Delivery Tunnel South was constructed in sandstones of the Clarens Formation. These sandstones presented few problems during excavation and this tunnel was bored 20 months ahead of schedule. It was anticipated that the Delivery Tunnel North would be the most difficult to excavate as it runs through a succession of mudstones and sandstones. Hence this tunnel is being excavated by a double-shielded tunnel boring machine which can bore through varied ground and provide protec- tion against rock falls, while simultaneously installing precast lining segments. (Author)

Mines and quarries

965348 Technology improvements aid room-and-pillar coal mining C. J. Bise, Mining Engineering, 47(12), 1995, pp 1107-1110. The evolution in the state-of-the-art for room-and-pillar coal mining has resulted in safer, more reliable and more productive systems. Gains have been achieved in the Appa- lachian coalfields through a combination of innovative mining plans, n~re dependable extraction equipment and improvements in haulage and ground-control infracture. (from Author)

965349 State-of-the-art in mountaintop removal and contour mining M. A. White & F. A. Barata, Mining Engineering, 47(12), 1995, pp 1111-1114. Contour mining incorporated into a mountaintop removal operation helps control drainage, minimize downslope place- ments (overshots) and balance the mining ratios. While mountaintop removal optimizes the coal reserve, the nature of this method results in coal being produced with higher mining ratios. This is due to the topography of the mining area. However, another contributor to these ratio increases include previous mining operations in the area. The moun- taintop removal method of surface mining on this reserve began during the 1970s~ The top of the mountain is removed to uncover the most economically mincahle coal seams. The overburden and interburden removed axe placed in valley fills and backstacked on previously mined areas as required to produce the coal. Under ideal conditions, it is possible to extract nearly 100% of the ruinable coal, except for the outcrop barriers. (from Authors)

965350 Experiments with extending the upper extraction limit for Xinglongzhuang Coal Mine (in Chinese) Kang Yonghua, Geng Deyong, Ru Ruidian, Kong Fanm- ing, Fan Guoqiang & Huang Fuchang, Journal- China Coal Society, 20(5), 1995, pp 449-454. A systematic study of overlying strata failure trend for fully mecbaniTed coal face was made in industrial tests of mining under water-bearing layers without water drainage. Micro- analyses were also made to assess quality of water-resistance rock pillars. Monitorin]~ of underground environmental temperature field was conducted as one of the forecast measures for safe mining. The design principle of water- resistant coal pillar for whole mining area was worked out. (from English summary)

965351 Geochemical conditions of mining steep coal beds V. N. Kulakov, Journal of Mining Science, 31(2), 1995, pp 136-143; translated from: Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, 2, 1995, pp 56-62.

EXCAVATIONS:MINES & QUARRIES

The present article opens a series of publications devoted to the problem of mining steep coal beds and which are the result of the author's many years of investigations. The materials include a study of the mechanism of moving of the undermined mass, investigation of the change in rock pressure depending on mining and geological factors, including with increase of depth of mining operations, evaluation of the technologies and means of mechanization being used with respect to geomechanical conditions, scien- tific and technical substantiation of new technologies and means of large-scale mechanization, pilot-scale tests, and recommendations on the further improvement of technologies and equipment for mining steep beds. (from Journal transla- tion)

965352 Quantifying the cost of dilution in underground mines R. C. Pakalnis, R. Poulin & J. Hadjigeorgiou, Mining Engineering, 47(12), 1995, pp 1136-1141. Approximately 51% of all ore production in Canadian underground metal mines is derived directly from open-stope operations. This method requires that large excavations remain open until the ore is extracted with a minimum acceptable level of dilution. A survey of underground mines in 1988 reported that a major factor in their closure was uncontrolled dilution. It has been reported that 40% of openstope operations were experiencing dilution in excess of 20%. This paper reports on the various definitions of dilution, on the methods of stope design that are presently used with the objective of reducing dilution and on a recently available survey technique that enables dilution to be quantified. (from Authors)

965353 Application of ground penetrating radar in underground coal mine (in Chinese) Zhang Jincai & Ru Ruidian, Journal - China Coal Society, 20(5), 1995, pp 479-484. The penetration ability of a radar wave is an important index for evaluating the application of radar in an underground mine. Pentration ability depends on attenuation coefficient of electro-magnetic wave in media. The smaller the attenuation coefficient, the greater the penetration ability of radar wave is. The attenuation coefficient increases with the increase of medium conductivity. The media in underground mine are coal seam, sandstone, shale, limestone of low conductivity. Their attenuation coefficients are small and radar waves have high penetration ability in these rocks. Theoretically, it is feasible to use GPR underground. Examples are given to describe a filtering method to eliminate underground inter- ference and selection of filtering parameters. (from English summary)

%5354 Longwalls aid productivity in Appalachian coal mining S. L. Bessinger, Mining Engineering, 47(12), 1995, pp 1103- 1106. The need for improved safety and productivity brought about the introduction of longwall mining to the Appalachian coal fields. Current initiatives to improve productivity and safety are focused on automatiof~ and the effects of scale in equipment design. Longwall roof-supports, shearers and face-conveyors have changed significantly. Panel layouts have evolved to include larger total tonnages and provide for more rapid development of gate-entries. These advance- merits have improved longwall productivity and new produc- tion records are continually being set. (from Author)

965355 The anthracite smokers of eastern Pennsylvania: Ps2(s)-T stability diagram by TL analysis G. B. Stracher, Mathematical Geology, 27(4), 1995, pp 499- 511. Coal seams and culm banks associated with mine fires in the anthracite region of eastern Pennsylvania have been burning

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for decades. Many of the fires may have ignited by spontaneous combustion or by the burning of trash. Minerals associated with the combustion of anthracite form by the condensation of gas exhaled through surficial gas vents or 'anthracite smokers.' A Pressure-Temperature (P-T) stability diagram is constructed for the condensation of orthorhombic sulfur from anthracite gas using 'Thermodynamic Loop Analysis' (TL analysis). This method of analyzing chemical systems incorporates Kirehhoff's Law into a four step procedure structured around a closed thermodynamic cycle or 'thermodynamic loop'. (from Author)

965356 A history of mining in the Bathurst area, northern New Brunswick, Canada W. M. Luff, CIM Bulletin, 88(994), 1995, pp 63-68. The Bathurst area has recorded mining production as early as 1837, mainly from the well-known massive sulphide deposits, but vein, gossan, and a variety of other deposits have also been mined. A number of 'firsts' have been noted in the Bathurst area. The A Zone deposit, located in the Heath Steele area, was the first in the world discovered using airborne electromagnetic methods. Heap leaching of gold from the gossan zone at Caribou was the first operation of its kind in Canada. The Keymet mine was the first base metal (lead-zinc) mine in New Brunswick. For the past few years. The Brunswick No. 12 mine has been one of the largest zinc mines in the world. (from Author)

965357 Polish lignite mine provides major source of power ANON, Coal International, 243(6), 1995, pp 222-223. This short feature describes the Belchatow opencast mining operation in Poland. The pit supplies coal for a 4320 MW power plant which produces 20% of the country's energy. (Author)

965358 Developing a property offshore: the Omal Gold Mines story G. H. Veillette, CIM Bulletin, 88(993), 1995, pp 53-58. Omal Gold Mines Ltd. is the operator of a large-scale open pit gold mining operation located in Guyana, South America. The remote location of the mine requires an extensive logistics support to ensure .adequate material supplies. This paper describes the mine construction, its commissioning and the current operations, putting the emphasis on the logistical problems enountered in mine development in a developing country as compared to North American operations. (from Author)

965359 Assessment of the prospects of development of in situ coal gasification in the Kuznetsk Basin A. A. Myasnikov & S. N. Lazarenko, Journal of Mining Science, 31(2), 1995, pp 144-146; translated from: Fiziko- Tekhnicheskie Problemy Razrabotki Polezynkh Iskopaemykh, 2, 1995, pp 73-76. An analysis of the prospects of development of the ICG in situ coal gasification method in the Kuzbas provides for a study of the given problem in economic, geological, and ecological aspects. An analysis of the cost effectiveness and expediency of developing the ICG method in the Kuzbas presumes first of all a detailed study of the fuel balance of the Kuznetsk basin, a comparison of the coal and gas compo- nents of this balance, and determination of the gaseous fuel (which the gas of ICG is) requirement of enterprises of the Kuzbas. The total fuel consumption in the Kemerovo region in 1990 was 19.7 million tons standard fuel, of which coal fuel was 16.7 million tons standard fuel. Retention of the primary use of solid fuel is anticipated in the near future in the fuel balance of Siberia, including in the Kemerovo region. (from Journal translation)