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Summary A two dimensional finite element procedure is applied to simulate a coal mining excavation sequence. A procedure with linear solution steps is developed and applied to an idealized mountain cross-section with exceptionally thick coal seams and large dip angle. The results provide information on pillar pressure, floor and roof stability, displacement characteristics and surface subsidence.The results presented here were obtained in the course of research sponsored by the Department of Energy, Mines and Resources, Grant No. 69-2570. 相似文献
2.
P. R. Sheorey 《Geotechnical and Geological Engineering》1984,2(2):133-140
Summary Indian coal measures have widely varying caving characteristics. The maximum roof span of a longwall or depillaring panel at the time of nether roof collapse is shown to have a direct relation withRQD from a study of 12 case histories. A similar relation between maximum unsupported span of openings and rock mass quality as defined by theQ-system was also demonstrated. A simple nomogram is presented to predict the face advance required to cause roof collapse when theRQD or rock mass quality is known. 相似文献
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Summary This paper deals with the determination of subsidence parameters on a sloping ground surface above a completely mined underground panel in an inclined seam. A rays projection method is analytically developed to derive the subsidence components on the sloping ground surface from the corresponding ones on an assumed equivalent horizontal surface through the point of the mean elevation of the sloping surface above the extracted panel. Using the derived equations, the variation of subsidence with the inclination of the ground surface is analysed. An example is given to illustrate the application of the rays projection method in predicting subsidence effects on a sloping surface. 相似文献
5.
David C. Oyler Christopher Mark Dennis R. Dolinar Russell C. Frith 《Geotechnical and Geological Engineering》2001,19(2):137-168
Unusual circumstances may require that a longwall retreat into or through a previously driven room. The operation can be completed successfully, but there have been a number of spectacular failures. To help determine what factors contribute to such failures, a comprehensive international database of 131 case histories has been compiled. The cases include six failures where major rock falls occurred in front of the shields, and seven even more serious failures involving major overburden weighting. The case studies suggest two types of room failure mechanism. The first is a roof fall type failure caused by loading of the immediate roof at the face as the fender or remnant longwall panel narrows. The second is an overburden weighting type failure caused by the inability of the roof to bridge the recovery room and face area, and affecting rock well above the immediate roof. The data indicate that the roof fall type of failure is less likely when intensive roof reinforcement (bolts, cables and trusses) is employed together with higher-capacity shields. The overburden weighting failures, in contrast, occurred when the roof was weak and little standing support was used. Weighting failures were not greatly affected by the density of roof reinforcement. In one of the overburden weighting cases, in a Pittsburgh coalbed mine, stress cell, convergence, bolt load and extensometer data have been used to analyze the failure in detail. 相似文献
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C. P. Liao 《Geotechnical and Geological Engineering》1993,11(4):235-247
Summary The fuzzy influence function method takes account of the effect of the rock mass around the edges of a panel on the surface subsidence. Unlike conventional influence functions, the shape and value of the fuzzy influence function varies with both the position of points calculated on the surface and the position of elements integrated in the extracted area underground. Consequently, the results obtained by using the fuzzy influence function method can automatically give rise to a shift of the inflection point towards the goaf and asymmetry in shape. The accuracy of the calculation is also improved. Case-history examples of mining subsidence engineering show good agreement between the results from geodesic measurements and those calculated from the fuzzy influence function method. The programs for back-analysis of parameters can approach satisfactory results of optimization. 相似文献
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Józef Kabiesz 《Geotechnical and Geological Engineering》2006,24(5):1131-1147
During hard coal mining operations conducted under conditions of rockburst hazard, one of the most important preventive measures
can be the prediction of occurrence time and location of the strong seismic mine tremors of energy E
s ⩾ 104 J. This is a very difficult task and the way it is being currently performed appears to be unsatisfactory. Therefore, attempts
have been made to use neural networks, specifically trained for this application. The paper presents an approach for determining
an influence of the type and shape of the input data on the efficiency of such a prediction. The considerations are based
on a selected example of the seismic activity recorded during longwall mining operations conducted in one of the Polish mines. 相似文献
8.
Roman Magda 《Geotechnical and Geological Engineering》1985,3(4):271-293
Summary The basic foundations of an integrational method of modelling and estimating the economic effectiveness of a deep coal mine production process is presented. The method is founded on the concept of integration of smaller structural elements into larger ones in order to obtain a representational model of the whole mine production process. It involves analysis of the spatial, engineering and time structures of the mining process. The basic structural unit of the production process is the elementary time interval,T, together with a linear function of the approximate intensity of financial outlays or effects. The repeated integration of these elementary time intervals within the spatial, engineering and time structures of the mine production process can be extended to model the whole mine or discrete spatial structure elements.The model may be used to investigate the trends of financial outlays and effects, and their current values updated for arbitrarily assumed updating moments. The model can also be used as an investigation tool for analysing the economical effectiveness of the mine production process. 相似文献
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Monitoring of strata control parameters and behaviour of a powered support was carried out during an experimental trial of a mechanized longwall sublevel caving face for exploitation of a 7.5m thick coal seam. Field observations indicated that the requirement of support density for underwinning of top coal by sublevel caving under intact strata is different from that for underwinning under broken and fractured rock mass. Analysis of the leg closure observations and support resistance variations during different mining cycles showed rapid increase of the setting load density of the support in relation to the yield load density. This resulted in a large amount of leg closure during mining cycles of the sub level caving face under broken rock strata. Due to operational constraints, the field observations could not provide enough information to visualize the behaviour of the overlying rock strata. Simulation of the field conditions was therefore performed on a physical model to bridge this gap of information. Results of laboratory investigations on the physical model are combined with those of the field to explain the critical behaviour of the support system during sublevel caving under broken rock strata. 相似文献
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太原煤炭气化集团有限责任公司龙泉矿井是新建的大型现代化矿井，依据该矿井大部分钻孔揭露的煤层厚度大于6．0m．在综合分析该矿井开采深度，煤层厚度、煤层结构、夹矸层数及其硬度和厚度、煤层顶板岩性及其厚度、煤岩体裂隙发育程度等地质因素基础上，考虑瓦斯聚积程度及煤尘量等影响因素，对长壁综采分层开采法、综采一次采全高采煤法和长壁综采放顶煤采煤法三个采煤方案进行优选，最终选定该矿采用长壁综采放顶煤采煤方法，依靠地压破煤及自重放煤．提高厚煤层的回收率。 相似文献