30 / 2025-07-10 16:11:08

Deformation and Failure Mechanisms of Slopes with Different Shapes Under Repeated Mining Activities and the Evolution Characteristics of Fracture Networks

Repeated Mining Activities; Different Slope Shapes; Numerical Simulation; Image Recognition; Disaster Mechanisms; Fracture Network

Frequent mine collapse and landslide disasters caused by underground mining activities occur in the southwestern mountainous regions of China. The disaster modes of these landslides are complex and severely harmful, and the slope deformation evolution process and disaster mechanisms under different mining conditions require further investigation. This study focuses on slope shape, establishing three conceptual models of mining slopes: linear, concave, and convex-concave. Using PFC²D numerical simulation, PCAS image analysis techniques, and fractal theory, the deformation failure mechanisms and fracture network evolution patterns of mining slopes with different shapes under repeated mining activities were systematically revealed. The results show that, under the influence of slope shape effects, the stress concentration points of the three types of slopes (linear, concave, and convex-concave) under mining activities are located at the toe of the slope, the middle of the slope body (where there is a sharp change in slope angle), and the protruding part, respectively. The deformation and failure modes are: mining-induced subsidence-collapse-sinking-tensile failure-creep-slip, mining-induced subsidence-collapse-sinking-tensile failure-sliding-bending-shear failure-sliding, and mining-induced subsidence-collapse-sinking-tensile failure-tilting-shear failure-collapse. The fractal dimension increment and probability distribution index of the overlying rock fracture network first increase and then decrease. The fracture rate, fracture number, and fracture entropy continuously increase, and the fracture network evolution under repeated mining conditions exhibits a cyclical process of "formation-expansion-penetration-expansion-compaction." The fracture morphology evolution occurs in three stages: (1) development of bedding fractures, (2) interconnection of vertical, inclined, and bedding fractures, and (3) expansion of original fractures with partial compaction and the formation of a small number of new fractures. The research results provide a reliable reference for early warning standards, targeted prevention and control, subsequent remediation, and reinforcement of mining slopes.