Experimental and numerical investigation of stress spatiotemporal response of fault plane during underground coal seam advancement

Fault slip induced by coal seam mining is a major hazard that can trigger dynamic disasters such as coal bursts. Understanding the evolution of shear and normal stress on the fault plane is essential for revealing the mechanical mechanism of mining-induced fault activation. Based on physical experiment and numerical simulation of the 21,221 mining face in Qianqiu coal mine, this study investigates the stress spatiotemporal response during mining face advancement. Results show that shear stress fluctuates in repeated cycles of abrupt drop followed by rapid rise, with cycles becoming less frequent and intense farther from the coal seam, indicating a distance-dependent disturbance effect. Mining activity also induces migrating stress relief and concentration zones, the relief zone expands toward the near coal seam side while the concentration zone shrinks and shifts away. A rise in normal stress accompanied by a drop in shear stress serves as a key slip precursor of fault, whereas a simultaneous sharp decline in both shear and normal stress marks fault instability and energy release. Therefore, coupled monitoring of normal and shear stress evolution law provides valuable early warning of fault slip risk.