关键词: 厚表土薄基岩, 覆岩破断, 应力演化, 微震监测, 数值模拟

Abstract: In view of the engineering problem that the mining of thick topsoil and thin bedrock strata in deep mines is prone to regional severe mine pressure behavior，the 7303 working face of Zhaolou Coal Mine is taken as the research object，and the numerical simulation and KJ551 microseismic field monitor⁃ ing methods are comprehensively used to systematically analyze the stage-by-stage fracture evolution law and mining vertical stress response characteristics of the overburden during the whole mining process of the working face. The numerical model reproduces the whole process of bending separation and caving of imme⁃ diate roof and multi-layer key strata under different advancing distances. The simulation results show that the immediate roof first breaks when the working face advances 20 m，which is basically consistent with the field measured 18 m caving step distance. The periodic weighting step distance of the basic roof is about 20 m，and the maximum vertical stress of the coal wall on both sides of the goaf can reach 37.5 MPa. The on-site microseismic monitoring shows that the maximum development of overburden fracture is 140 m above the coal seam，and the 114 m thick bearing bedrock is completely penetrated. The upper thick top⁃ soil load is transmitted to the front coal body and roadway through the broken bedrock，forming the overall overburden disturbance of 7301 and 7303 composite stopes. The microseismic intensive area and high stress area are highly consistent with the location of on-site mine pressure，which verifies the linkage mechanism of stress-driven overburden rock fracture and mine pressure disaster. The numerical simulation and field monitoring results confirm each other，which proves that the model can accurately restore the whole process of overburden rock migration and stress redistribution in thin bedrock strata. The research re⁃ sults can provide theoretical reference for deep safe mining of mines with similar occurrence conditions. At the same time，KJ551 microseismic monitoring system has shortcomings in noise reduction ability in deep high ground stress environment. In the future，it is necessary to develop intelligent noise reduction algo⁃ rithm and well-ground collaborative monitoring scheme to improve early warning accuracy.

Key words: thick topsoil and thin bedrock, overburden rock fracture, stress evolution, microseismic monitoring, numerical simulation