Study On Mining Effect And Dynamic Response Characteristics In Normal Fault-affected Area

The fault is a geological structure that is common in the working face and nearby,and has hidden dangers.It has a major impact on the mining face design,reasonable roadway support,safe production and mining technology.The occurrence state of the fault and the mining method and arrangement of the working face along the fault are not the same,and the risk of mining action and its induced disaster will inevitably vary.The mining stress and surrounding rock structure near the fault are mutated,and the rock burst,support crushing,roadway instability and other disasters are coupled,which poses a serious threat to the safe production of coal mines.In this study,rock mechanics test,similar simulation test,theoretical analysis,numerical simulation and field measurement are used to systematically study the mining effect and dynamic response characteristics of the fault affected area,and the research results are verified by engineering examples.The following research results are obtained:(1)Based on the uniaxial compression and acoustic emission tests in laboratory,the stress evolution and macro-failure laws of fault plane under dip angle,roughness and surrounding rock strength are analyzed,and the influence of fault characteristic parameters on fault instability characteristics is obtained by combining with acoustic emission(AE)characteristics.(2)Based on the similar simulation experiment,the law of overlying strata movement,the law of roof subsidence,the distribution characteristics of normal stress on the fault,and the distribution characteristics of fault slip are studied during the working face advances to the fault in the hanging wall and footwall,moreover,the model of fault activation under different sequence of mining the hanging wall and footwall of the fault is revealed.Based on the elastoplastic mechanics and plate ultimate yield theory,the overburden failure model under the different mining sequences with the typical boundary conditions is established,and the weakening characteristics of overburden bearing capacity under the influence of faults are analyzed.(3)A numerical model is established to describe the characteristics of compaction bearing capacity and stress recovery of gangue in goaf.The mining effect and dynamic response under the condition of vertical fault strike mining are simulated and studied.The influence law of fault dip angle on fault stability is discussed.The relationship between overburden movement,stress field of fault zone and induced dynamic disaster is revealed.(4)The numerical model of working face advancing along fault strike is established,and the evolution law of mining stress under different fault coal pillar widths is simulated and studied,in addition,the influence of fault coal pillar width and fault dip angle on fault activation is analyzed.(5)The mechanism of induced rock burst under dynamic and static combination is analyzed,and the mechanism of fault rock burst under dynamic and static loads is revealed.The dynamic response characteristics of surrounding rock under the dynamic loading of fault-affected area are simulated by using the dynamic calculation function of FLAC2D numerical simulation software.The dynamic response of the surrounding rock of the roadway under the dynamic loading disturbance of the hanging wall and footwall face mining is studied.The effect of the seismic source height on the impact damage of the roadway is analyzed,and the dynamic evolution process of the deformation and failure of the roadway after fault activation is reproduced.