Unraveling the Dynamic Failure‐Stress Feedback Mechanism in Mining Overburden Through the PIV‐DEM Synergistic Analysis

ABSTRACT To investigate the failure of overburden and the internal stress evolution feedback mechanism during mining, this study conducted laboratory physical experiments and discrete element method (DEM). In the physical model, overburden deformation was extracted using particle image velocimetry (PIV). The results show that during the mining process, the contact orientations on both sides of the goaf gradually incline, while those in the water‐conducting fracture zone become more uniformly distributed. In the continuous deformed zone, especially within the primary key stratum, horizontal contact orientations progressively become dominant. Based on the coupled stress–deformation evolution, the mining process can be divided into three stages: the initial stage, the arch formation stage, and the arch expansion stage. The stress drop region closely resembles the deformation patterns of soil arches. In the initial stage, the stress drop region appears columnar and extends directly to the surface, with movement mainly concentrated near the coal seam. During the arch formation stage, the stress drop region begins to develop into an arch shape, and horizontal stress starts to concentrate within the primary key stratum. Locally, the rear deformation zone gradually stabilizes, while the overlying strata begin to move. With ongoing mining, the strata in front of the goaf also start to move. In the movement zones, stress relatively drops, whereas stress in the rear of the goaf tends to rebound. During the arch expansion stage, horizontal stress continues to concentrate within the main key stratum, and the movement zone is primarily characterized by horizontal expansion.