348A examined and methods of controlling methane emission into the mining environment discussed with reference to South African and Australian practices. Techniques considered are increased ventilation, bleeder roads in the goaf, drainage by surface boreholes, and cross measure boreholes. Pre-drainage and post-drainage methods are described.
896477 Potential rnckfalis in conventionally supported stopes - a simple probabtlistic approach Stacey, T R J S Aft lnst Min Metall V89, N4, April 1989, Pl11-115 Deep level gold mines in South Africa are surrounded by jointed and fractured rock, with fractures in general sub-parallel to the stope face. Rockfalls occur when there is failure through intact rock or natural joints that cut across the face parallel fractures to form blocks. Rockfall probability is evaluated for the case of point support only. Natural joints subparallel to the strike have controlling influence on falls. There is a significant probability of rockfalls with discrete support, which is increased by loss of support from a prop and decreased by the use of headboards oriented in the direction of the strike.
896478 Method of mining in Iongwall with inclined slicing consistent in the seam bottom Hao Zheming; Yu Yuesheng; Jing Ge Zhuang Proc International Symposium on Modern Mining Technology, Tnian, October 1988 P57-67. Publ Taian." Shandong Institute of Mining and Technology, 1988 The method described has been used successfully in thick and gently inclined coal seams. The seam is divided into 3 slices which are mined in ascending order. Strata control is by bulk caving. The second and third slices are taken after the roof from the previous slice is at seam bottom level. Shotfiring or mechanized extraction is possible. Increases in productivity, safety and economy are possible when compared to conventional thick seam mining.
896479 New development of special mining technology in China Li Baiying; Xiao Hongtian Proc International Symposium on Modern Mining Technology, Taian, October 1988 P68-75. Publ Taian." Shandong Institute of Mining and Technology, 1988 Mining beneath surface structures or surface water and above confined water is discussed. Prediction of strata and surface movement, monitoring of strata movement via borehole instrumentation, and prevention of water irruption from the damaged floor strata at the working face are considered.
89648O Cavability investigation of a stratabound copper deposit, Tong Kuang Yu Mine, Shanxi Province, China Lacy, W C Rock Mechanics as a Guide for Efficient Utilization of Natural Resources: Proc 30th U.S. Symposium, Morgantown, 19-22 June 1989 P159-165. Publ Rotterdam: A A Balkema, 1989 The ore bodies are located in metamorphosed tuffaceous rocks. An investigation into rock quality was carried out to correlate caveability with rock quality and evaluate distribution of rock quality types, likely fragmentation size distribution, stability of underground structures, dilution factors, and
residual stresses after mining. Initial work was based on drilling logs from 1955-56, and limited underground experience and mapping, and a few diamond drill holes. Comparison is made between initial predictions and underground experience.
896481 Experience with rib pillar extraction in South African collieries Beukes, J S Proc 1st Regional Conference for Africa, Rock Mechanics in Africa, Swaziland, 3-4 November 1988 P87-99. Publ Marshalltown: SANGORM, 1988 Use of rib pillar extraction in South African collieries is being adopted to increase the percentage of coal extracted. Experience of the technique in 5 collieries is described. Mining method and extraction method and support at each colliery are described. The method has been successfully applied, even where conventional pillar extraction proved hazardous.
896482 Modelling the subsidence and progressive mining of a shaft pillar using a distinct element model Broome, M T Proc 1st Regional Conference for Africa, Rock Mechanics in Africa, Swaziland, 3-4 November 1988 PlOl-I07. Publ Marshalltown: SANGORM, 1988 Subsidence of the shaft pillar at Luanshya mine has been monitored and analysed. The distinct element code, MUDEC, was used to simulate the large displacements associated with mining an orebody adjacent to the shaft pillar and to evaluate the effects of continued shaft pillar mining. Reasonable agreement with field data was achieved. Simulation of future mining suggests there would be no adverse reaction.
896483 Two cases of progressive pillar failure at collieries in Swaziland and Kwazulu Oldroyd, D C; Buddery, P S Proc 1st Regional Conference for Africa, Rock Mechanics in Africa, Swaziland, 3-4 November 1988 Pl19-136. Publ Marshalltown: SANGORM, 1988 Pillar failure was studied at 2 collieries. At the Emaswati colliery, several pillars in the accessway failed. Convergence meters were used to monitor failure and showed failure was linear, with no increase or decrease over time. It seems the dip played a major role in failure. At Zululand, excessive pillar spalling and roof cracks were noticed after 3 months. The rapid deterioration was monitored for 8 months, during which a new belt road was driven away from the pillars. The problem has now stabilised.
896484 Weeks Island Replacement Facility Nash, W R Proc 1987 Rapid Excavation and Tunnelling Conference, New Orleans, 14-17 June 1987 V1, P452-460. Publ Littleton: Society of Mining Engineers, 1987 When the Weeks Island salt mine was taken for the Strategic Petroleum Reserve, temporary and permanent extraction facilities were developed to maintain production. The interim mine was achieved via a drill and blast incline from the existing production level, and raise boring and roadheader excavation. The new mine involved sinking two new shafts using ground freezing where necessary, which were lined with a dynamic bitumen shaft liner, and drill and blast bottom excavation. Emergency grouting was needed to overcome groundwater problems in both cases.
~, 1989 Pergamon Press plc. Reproduction not permitted