Research On The Impact Of Risk Assessment And The Distribution Characteristics Of Fault Stress During Fully Mechanized Sublevel Caving Mining

Rock burst is one of the serious natural disasters of coal mine in the worldwide. Coal seams and the rock stratums of our majority coal mines have varying degrees of impact of bias, coal and rock outburst extremely serious in the critical depth, particularly with China's coal mining depth increasing by twenty metres a year, rockburst becoming more and more serious, and it has become one of China's major disasters which restricted the safety and efficient production of our mine. Disturbance stress of thick coal seam sub-level caving mining distributed abnormally. rockburst accured frequently. there are a lot of rock burst research to be done in theory, forecasting methods and integrated control of fault region.Xinglongzhuang coal mine has larger mining depth in mining area seven. Moreover, it adjacent to five mining area gob in the south, and mining coal pillar in the north. There are many fault in this area, so it need to remain more fault coal pillar, thereby greatly increasing the risk of impact.This paper in connection with the actual needs of rockburst control of Xinglongzhuang coal mine area seven, near mined-out area mining variation of dynamic stress and optimization of coal pillar width, mining-induced stress distribution of fault parallelled roadway, mining-induced stress transfer rule of fault parallelled face and rockburst danger zone was studied by using discrete element numerical simulation, theoretical analysis, field test research methods.Near mined-out area mining variation of dynamic stress and optimization of coal pillar width was studied by using discrete element simulation, and theoretical analysis. Studies have shown that:coal pillars leaving in the process of Mining, generate pressure superposition caused by both sides of the mined-out area, and form higher abutment pressure; as the face advanced, the bimodal stress in the coal pillar gradually merged, the stress peaks gradually increased the stress concentration zone up and down of the coal pillar and near it most likely to have rock burst; stress distribution of different sizes of coal pillar was studied, and combined with theoretical research and field realities reached a reasonable size of coal pillars of 43.8m-46.4m, provide a scientific basis for leaving a reasonable coal pillar in mining area seven of Xinglongzhuang coal mine. Based on the results, a 45m of mining area coal pillar was leaving in 7305 face.Evolution of mining stress and high stress concentration region of fault parallelled to the face was studied by using discrete element simulation. Studies have shown that:As the working face advanced from footwall to the fault abutment pressure gradually increased. with the increase of concentration of abutment pressure, may have an impact risk; After the face passed fault, Stress concentration is relatively small at first, then greater, finally tend towards stability; in the process of advancing away from the fault, the peak stress significantly less than the peak stress created in the coal pillar when the face advancing towards the fault.Mining stress transfer rule and high stress concentration region of fault parallelled to the roadway. Studies have shown that:abutment pressure rarely passed to the coal outside the fault due to the cut of the fault, high stress concentration area was created in front of the face. the pillar size smaller between roadway and the fault, the abutment pressure greater in the coal pillar, the rockburst risk was more easier to happen in the roadway.According to numerical simulation, the abutment pressure evolution and high stress concentration region was obtained.7305,7301,7302 face of high and moderate risk areas in mining area sevse was designated by using multi-factor analysis, provides a scientific basis for the rockburst monitoring and control.