Effects of the Quaternary aquifer water pressure on fault activation leading to roof water hazards

Fault activation is a common phenomenon during coal seam mining in proximity to faults. Fault activation significantly exacerbates the risk of roof water hazards through multiple mechanisms. To better understand the mechanism of roof water hazards caused by fault activation, numerical simulation and physical experiments were employed. By coupling FLAC3D with PFC3D, it was demonstrated that fault activation occurs in a phased manner, essentially involving the processes of shear failure and fracture propagation. During coal mining, fault activation induces stress concentration at fault ends and a substantial increase in the height of the water-conducting fracture zone. Furthermore, the degree of fault activation positively correlates with the advance distance; more active faults exhibit greater maximum subsidence per unit advance distance. Physical experiments demonstrate that fault activation exhibits a negative correlation with the pore water pressure required based on fault dip angle and width. These findings reveal that considering the influence of Quaternary aquifer water pressure on fault activation provides a theoretical basis and valuable insights for preventing and controlling roof water hazards during coal mining operations near faults.