Stability analysis of karst anti dip rock slope induced by underground coal mining - A case study of Jiguanling landslide, China

In recent years, the southwestern region of China has experienced a surge in significant mountain collapses, predominantly linked to underground mining operations. This investigation targets the Jiguanling area in Wulong, Chongqing, employing the UDEC numerical simulation technique to meticulously examine the deformation and failure characteristics, rock mass movement patterns, fracture evolution processes, and stress transmission mechanisms of anti-dip rock slopes composed of stratified rocks. These slopes are inherently susceptible to bending and tilting due to their own weight. Our findings elucidate that the predominant failure mode of anti-dip rock karst slopes is the inclined sliding (shear) type, which mirrors the fracture evolution mechanism as they extend in a quadrilateral pattern from the top and bottom plates of the mining area to the critical blocks at the rear and front edges of the slope. The disaster mechanism can be encapsulated as the "initial roof movement phase, direct roof collapse and crack propagation phase, critical block locking and sliding resistance phase, and deterioration phase". The four distinct stages of development and transformation encompass critical block slip (shear) and slope instability phases. An increase in coal seam thickness enlarges the deformation space in the lower part, while the dip angle of the coal seam influences the length and displacement range of rock fracture development. The mining sequence alters the stress failure mode of the underlying critical blocks, and the vertical height of the mining step distance modifies the potential sliding surface and failure mode of the underlying critical blocks. Ultimately, the distance between the goaf and the surface, along with the height of the mining impact, impacts the stability of the reverse slope. The results demonstrate that mining activities are the primary factor inducing the collapse of anti-dip rock slopes, with natural factors playing a secondary role.