Study On Fracture And Instability Law And Control Technology Of Overlying Thick Magmatic Rock

The fracture and instability of the overburden during coal mining is an extremely complex and extremely valuable research topic.Especially when the working face is covered with hard magmatic rocks of tens of meters or even hundreds of meters thick,owing to its special displacement,stress and energy evolution law,it is one of the hotspots and difficulties in the research of mining,geotechnical and mechanics.Geodynamic disasters,such as rock burst,mine earthquake and surface subsidence,caused by the breakage of hard and thick rock strata,seriously threaten the safe and efficient production of coal mines in China,which is a major and difficult problem to be solved urgently.Therefore,as the basis of the study on the mechanism of coal mine geological dynamic disasters,the study on the law of coal and rock mass breakage and instability in the process of mining with thick magmatic rocks has important theoretical guidance and reference significance for deepening people’s understanding of the mechanism of dynamic disasters and taking corresponding preventive measures in time.Based on this,this thesis studies the movement law of overlying strata,stress evolution law of surrounding rock and energy dissipation characteristics during mining under thick magmatic rock by using the methods of theoretical analysis,numerical simulation and field measurement,and the prevention and control effect of filling mining on dynamic disasters is analyzed.The main research results are as follows:Firstly,the whole process of magmatic rock deformation and subsidence to breakage and instability under the condition of overlying thick magmatic rock in Yangliu Coal Mine is systematically simulated by using the continuum mechanics analysis software FLAC3D numerical system.Based on the theory of elastic foundation beam and energy method,the mechanical analysis of the breaking step and elastic energy accumulation and dissipation of thick magmatic rock is carried out.The evolution process of displacement field,stress field and energy field in the process of inducing breakage and instability of thick magmatic rock is studied numerically,and the mining effect of magmatic rocks with different thickness and occurrence horizons is compared and analyzed.Secondly,FLAC3D numerical simulation system is applied to study the mining effect of two different mining schemes,which are sequential mining by caving method and sequential mining by combining caving method with filling method.The dynamic disaster control effect of filling mining on thick magmatic rock mining is analyzed by comparing displacement field,stress field and energy field.Finally,the above research contents are verified and analyzed by the measured data of surface subsidence of 10414 working face and microseismic energy distribution law of 10416 working face in Yangliu Coal Mine.