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Strata movement and the risk of rock bursts (in German and English)
149A are: behaviour of coal measures rocks; design of rooms and pillars; tunnels and drifts: shafts and insets; strata deformation above Iongwall excavations, access roadways and roadside packs: coal face strata deformation and support: and bursts and instability. 855087 Rock stability analysis by acoustic spectroscopy Hanson, D R Min Engng V37, NI, Jan 1985, P54-59 Acoustic vibration spectra of impacted rock slabs were examined to characterise the behaviour of unstable mine roof rocks. Field and laboratory tests showed an enhancement of power spectra in the 200-500Hz range for both hard and soft "drummy' rocks. The spectral difference disappeared as frequency increased and so the technique of comparing energy in high and low frequency bands was used to measure rock stability. A lightweight prototype field instrument gave reliable measurements of block stability under noise conditions which would seriously affect the accuracy of standard assessment methods. 855088 New ideas for mining underground Dayton, S H Engng Min J V186, N1, Jan 1985, P52-55 The techniques adopted by Inco are described. Ground control by hydraulically placed and cemented backfill and local control by a spray-on fibreglass reinforced epoxy resin, underground stoping using the vertical crater retreat method and blast damage control in underground and open pit mines are discussed. 855089 Convergence of roads at depths of up to 1400m at Ibbenburen colliery (In German and English) Kammer, W; Rohrs, H Gluckauf V120, N20, 18 Oct 1984, P1308-1318 (german), P346-349 (english) Initial measurements in the Ibbenburen haulage roads suggest that convergences at present customary in the Ruhr can be anticipated during drivage at greater depths. Roadway control has been improved for larger road cross-sections by using increased support. Road and support deformation are continuously monitored and used to check advance calculations. 855090 Rock pressure problems at extreme depth (In German and English) Irresberger, H Gluckauf 11121, N4, 21 Feb 1985, P276-283 (german), P101103 (english The present state of knowledge of rock pressure at extreme depth is reviewed. Sectors dealt with include in-seam rise headings, faces, gateroads, supports and full face drivage. 855091 Strata movement and the risk of rock bursts (In German and English) Brauner, G Gluckauf V121, N5. 7 March 1985, P351-361 (german), P126-129 ~english ) Lateral elongation and thrusts of the coal wall, together with pressure effects normal to stratification, can give useful information to assist in rockburst prediction. Small, long-term movements may indicate eventual build-up of a high stress. Short term increases, in conjunction with an increase in pressure normal to stratification, may mean imminent danger. This is
explained in terms of irregular expansion of fractures in the seam. A number of case studies are presented. 855092 Considerations on improved roadway driving results through conventional methods in West Germany (In French) Wild, H W Industrie Minerale V66, N2, Dec 1984, P669-676 Factors affecting the rate of advance of roadway driving, using blasting techniques, in West German coal mines are discussed. Means to improve driving performance include use of larger cartridges, hydraulic cutting, strict application of blasting patterns, pre-fragmentation blasting and lowered driving sections. 855093 Design of pillars in the shrinkage stoping of a South African gold mine Kersten, R W O J S Aft Inst Min Metall V84, N i l , Not: 1984, P365-368 A back analysis approach is used to calculate pillar strengths in the Agnes gold mine. Results obtained are comparable with those from other accepted formulae. It was found that a stress level of more than 70MPa for the width of combined (crown and sill) pillars causes failure of reef drives as well as tops and bottoms of stope side walls. Pillar dimensions were calculated for a number of working depths. As depth increases, so does pillar size, with consequent fall in percentage extraction achievable. At depths greater than 650m, shrinkage stoping becomes uneconomic and alternative extraction techniques will be necessary to exploit reserves below this depth. 855094 Mining by large diameter blastholes at the El Soldado mine, Chile g i n Mag March 1985, P264-265 Two mining methods, large blast hole (LBH) and vertical crater retreat (VCR), have been used in an underground copper mine. Both are described and formulae for calculating blasting variables are given. VCR gave good fragmentation, reducing secondary blasting requirements, and minimised stope wall damage but had a poorer drilling index, higher explosives consumption and lower productivity when charging explosives to the holes. 855095 Underground methods of extraction of thick coal seams - a global survey Ghose, A K Min Sci Techn V2, N1, Dec 1984, P17-32 A review of current developments in exploitation of thick seams. The available reserves and mining techniques used in many countries are listed. The use of room and pillar methods, single-pass and multislice longwall mining, underwinning and hydraulic mining are specifically considered. 69 refs. 855096 Theory and practice of highly mechanised cut and consolidated fill method in China (In Chinese) Ma Yinfang Nonferr Met 1/37, N1, Feb 1985, P19-25 Current developments of cut and fill mining methods in China are reported. The present methods with drilling by jumbo, mechanical ore removal and filler transport by pipeline are efficient and economical. Details are given of the mining operations and layout, the filling procedures and materials requirement.
explained in terms of irregular expansion of fractures in the seam. A number of case studies are presented. 855092 Considerations on improved roadway driving results through conventional methods in West Germany (In French) Wild, H W Industrie Minerale V66, N2, Dec 1984, P669-676 Factors affecting the rate of advance of roadway driving, using blasting techniques, in West German coal mines are discussed. Means to improve driving performance include use of larger cartridges, hydraulic cutting, strict application of blasting patterns, pre-fragmentation blasting and lowered driving sections. 855093 Design of pillars in the shrinkage stoping of a South African gold mine Kersten, R W O J S Aft Inst Min Metall V84, N i l , Not: 1984, P365-368 A back analysis approach is used to calculate pillar strengths in the Agnes gold mine. Results obtained are comparable with those from other accepted formulae. It was found that a stress level of more than 70MPa for the width of combined (crown and sill) pillars causes failure of reef drives as well as tops and bottoms of stope side walls. Pillar dimensions were calculated for a number of working depths. As depth increases, so does pillar size, with consequent fall in percentage extraction achievable. At depths greater than 650m, shrinkage stoping becomes uneconomic and alternative extraction techniques will be necessary to exploit reserves below this depth. 855094 Mining by large diameter blastholes at the El Soldado mine, Chile g i n Mag March 1985, P264-265 Two mining methods, large blast hole (LBH) and vertical crater retreat (VCR), have been used in an underground copper mine. Both are described and formulae for calculating blasting variables are given. VCR gave good fragmentation, reducing secondary blasting requirements, and minimised stope wall damage but had a poorer drilling index, higher explosives consumption and lower productivity when charging explosives to the holes. 855095 Underground methods of extraction of thick coal seams - a global survey Ghose, A K Min Sci Techn V2, N1, Dec 1984, P17-32 A review of current developments in exploitation of thick seams. The available reserves and mining techniques used in many countries are listed. The use of room and pillar methods, single-pass and multislice longwall mining, underwinning and hydraulic mining are specifically considered. 69 refs. 855096 Theory and practice of highly mechanised cut and consolidated fill method in China (In Chinese) Ma Yinfang Nonferr Met 1/37, N1, Feb 1985, P19-25 Current developments of cut and fill mining methods in China are reported. The present methods with drilling by jumbo, mechanical ore removal and filler transport by pipeline are efficient and economical. Details are given of the mining operations and layout, the filling procedures and materials requirement.