| With the development of the national economy, the increasing demand for coal, but China’s open-pit mining of coal accounts for a little proportion. Pit mining comprises95per cent of exploitation of coal nowadays. As the depth of exploitation is increasing continuously, the operating environment degraded gradually, prominent mine gas amount increased. In the process of underground mining activities, the liberation layer(the protective layer)covering the face rock decorated and moved、 destructed, such as coal and gas outburst disasters became more frequent,the threats was growing more intense,it restricted the sustainable development of the mining enterprises severely. In the process of coal mining, because the mass disturbance produced a variety of beneficial gas circulation "channels (fracture)". If the law of rock mass deformation and failure could recognize, timely took corresponding protection measures, it will reduce such occurrences.Through the collection and the consult large amounts of literature material, based on the mining geological conditions and rock mechanics laboratory tests, it used laboratory test、theoretical analysis and numerical simulation analysis of a combination of research methods, some research harvest were as follows:(1) Be based on "Masonry beam" structure theory, its deformation had been affected by coal mining height, rock mechanical properties and other factors. Be based on the mechanic analysis of roof key block, established the geologcial prototype of dynamic basic roof, combined with the characteristics and mechanical parameters of rock mass in Linhuan coal mining, generation of mechanical model, this paper deduced its two kinds of fracture instability extreme conditions:slide and rotation deformation. While i≥0.3cosα1-sinα1/1-0.6sinα1, rock mass would occurrenced sliding instability. while T≥a·η·σc, in the state of deformation instability. With the help of overall stope rock mechanics model, exposed that the7#coal seam roof subsidence would decrease with increasing support resistance, and roof rotary angle was direct ratio relation, and with was proportional to the Young’s modulus, Young’s modulus was found to increase at the same time, roof subsidence had reached the corresponding values.(2) Made full use of the theory of fracture mechanics, derived to calculate the stress of surrounding rocks in three different boundary conditions. By detailed analysis of the system for17116working face in Linhuan coalmine stope edge damage zone, in Mohr-Coulomb criterion, in plane stress and plane strain condition, the7#coal bottom layer of the maximum failure depth were10.6m、11.11m and the maximum horizontal distance of2.83m. Meanwhile, it used theory of plasticity to calculate the maximum failure depth is23.0m. （3）Simulation results showed that, the vertical displacement was obvious inI7116’s roof and floor of Linhuan coalmine in Huaibei, the maximum verticaldisplacement were respectively55mm and49mm, to investigate process of theevolution stress and distribution of elastic-plastic zone, finally the theoreticalcalculation were compared with numerical simulations, it has high reliability.Through the study on deformation of the7#coal seam roof and floor, it was ableto preliminary forecast coal and gas outburst regional and gas accumulation sites inLinhuan mine I7116woking face. Thus, the gas drainage direction was cleared、regionar clearly to provide powerful technical support for gas prevention in theprocess of mining activities effectively, importanted significance for theimplementation of coal mine safety and high efficiency production. At the same time,a great guiding function for similar conditions of mining or coal mine safetyproduction. |
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