Influence of reverse fault activation on coal mine rock burst under different dip angles and stiffness

The activation of reverse faults can significantly increase the risk of rock burst, as the fault's dip angle and stiffness control the accumulation and release of energy that triggers such events. To assess the impact of varying fault dip angles and stiffness on rock burst risk in coal mines, this study uses the F16 reverse fault in Gengcun Coal Mine, located in the Yima mining area, as a case study. Through a combination of theoretical analysis, numerical simulations, and field monitoring, the study investigates how changes in fault dip angle and stiffness influence the evolution of the stress field in the working face and the activation-induced instability of the fault. The results show that when the dip angle of the reverse fault exceeds 60°, significant concentrations of shear and vertical stresses occur, increasing the slip risk coefficient (β) and making the fault more susceptible to activation. Additionally, when the fault stiffness ratio is below 1/5, the peak abutment stress ahead of the working face rises, and horizontal displacement grows nonlinearly, creating a “stress barrier” effect. This intensifies energy accumulation in the coal seam and elevates the risk of rock burst. Using the F16 reverse fault as an example, it is shown that the 13200 working face at Gengcun Coal Mine lies within the fault's influenced zone. Monitoring data from the F16 fault reveal that mining activities at the 13200 working face triggered the activation of the fault, leading to the concentrated release of accumulated energy in the coal-rock mass and the occurrence of five high-energy microseismic events. This study offers valuable theoretical insights and practical guidelines for predicting and preventing fault-induced rock burst.