Mining Stress Field Evolution And Experimental Study On Failure Law Of Overlying Strata

Overburden rock affected by mining,rock stress field and rock structure were damaged or deformed.As the research of underground mining roof caving patterns,and the goaf overburden accumulation of gas migration channel distribution,gas accumulation and intensive judgment places migration channel distribution area,we need to the mining stress field evolution and overburden rock fracture zone is studied.By using the overlying strata along strike and tendency profile similar materials simulation experiment,the spatial morphology and fracture of overlying rock destruction is solid distribution in time and space related problems.By using the finite difference numerical simulation software FLAC^3Dcalculation The evolution and distribution of stress field in the overlying rock are studied and analyzed.The main contents are as follows:?1?Through the analysis of similar experiments along the strike,the simulation tendency profile,obtained different profiles of overlying rock instability damage and caving are to follow certain rules,namely transverse abscission fracture-false roof,immediate roof caving-roof first caving?at the beginning of a trapezoid fracture zone?-roof pressure-key layer is now clear separation.According to the analysis of sinking curve of rock pressure and periodic law,the overlying rock destruction of basic steps or lost roughly steady bending and breaking rules articulated-gradually compaction;analysis of fracture zone that trapezoidal overburden failure leads to internal crack generation?with the separation?-Development-migration?fracture Zone?The regular circulation of compression?micro fracture zone?,after the shearer cut coal and the working face advancing for a period of time,the failure of the overlying strata and the development of fracture field have a certain time and space correlation.?2?The overlying rock stress field distribution was analyzed by FLAC^3D numerical simulation,the stress field evolution can be divided into"early stage of excavation?roof bottom not?-excavation?mid bottom roof?-late?bottom excavation rock compaction?in three stages.The stress and pressure relief the stress concentration can be divided into"expansion?peak concentration increasing?-pressure relief range of slowing growth trend slowed down/stress concentration?roof contact pressure relief area gangue?-stress recovery?stress concentration gradual?roughly several stages.Initial roof caving excavation stress field under the action of pressure relief.Support at both ends of the coal wall,cut off and working face stress concentration,And with the increase of Unloading Excavation distance,area to the top,the deep floor expansion.Caving roof floor contact,by supporting floor,pressure relief situation slowed,cut and working face overburden load decrease caused by stress concentration was reduced.The peak pressure relief area of floor began to be recovery area is linear and punctate distribution of expanding the scope of goaf overburden rock compaction.To some extent,the pressure relief area has no big change and stress recovery and expand the scope of China Unicom,the floor supporting force on the collapse of overlying rock to the upper cut off and transfer that the working face of coal wall stress focus tends to be stable gradually,thus the mining stress field evolution basic stability.