Abstract:
Fault structure is one of the important causes of rock burst, with the strongest destructive power, which can easily cause a series of problems such as coal mine overburden damage and surface subsidence, seriously restricting the safe production of fault structure areas of coal mine. To solve the problem of instability caused by the coupling of fault coal pillars in the fault structure area, microseismic monitoring technology is used to collect actual field data and analyze the mechanism of fault activation instability and rock burst using theoretical mechanical models. Two types of activation instability and disaster causing types are revealed (namely fault instability and coal pillar instability). Based on this, a numerical model is established to analyze the influence of fault conditions on the stress distribution characteristics of the working face during different stages of mining in the geological structure area. Combined with the distribution of microseismic events on site, a plan for preventing and controlling rock burst in the fault structure area is formulated. Research has shown that when the working face is mined to the fault area, a fault coal pillar area is easily formed between the working face and the faults. At the same time, it is affected by mining stress and the rupture of the hard roof and floor. The dynamic stress is unloaded in the horizontal direction and reflected as loading in the vertical direction. The decrease in the maximum principal stress of the fault leads to a decrease in the critical value of instability, and the degree of stress concentration in the working face increases. Therefore, when approaching the fault, fault activation instability is prone to occur, increasing the risk of rock burst in the fault structure area. The stress concentration in the intersection area of multiple faults is greater than that in the impact area of a single fault. Based on the actual geological mining conditions on site, a load reduction and energy release anti erosion plan is developed for deep hole blasting, large-diameter drilling pressure relief, and coal seam blasting pressure relief in the fault structure area. Based on microseismic monitoring and seismic wave CT inversion results, it is found that the microseismic frequency and energy in the same period and area decrease by 67%, and the stress concentration area of the coal rock mass in the fault structure area is significantly reduced, effectively avoiding the occurrence of rock burst in the fault structure area.