Study on the range of influence of faults on overburden fissures in the working face under repetitive mining action.

Repeated mining of coal seams in the fault structure area is prone to gas and roof disasters, so clarifying the influence range of faults is crucial for safe mining. This study uses a mine in Guizhou as its engineering background and applies fractal geometry theory and a fault mechanics model to quantitatively analyze the influence range of faults on overburden cracks under repeated mining. Through the fault zone rock slip-convexity mechanics model, it is revealed that the horizontal stress-to-vertical stress ratio and fault dip angle are the primary influencing factors of the model. Using UDEC numerical simulation and Matlab fractal computation, it is found that the overburden fractal dimension (D) evolution has gone through three stages of upgrading, downgrading, and changing dimensions, and there are two sudden increase points and two sudden decrease points. Combining the fractal dimension mutation characteristics and mechanical modeling criteria, it was determined that the influence range of the fault in the 3# coal seam was 40-100 m (influence width 60 m) and that in the 2# coal seam was 20-100 m (influence width 80 m). The research results provide a theoretical basis for gas extraction, roof support, and other disaster prevention and control in coal seam mining in the fault area, and have reference value for safe mining under complex geological conditions.