Failure Mechanism of Anti-Inclined Karst Slope Induced by Underground Multiseam Mining

Abstract

There occurred a lot of catastrophic landslides in Southwest China karst areas in recent years. This study numerically simulated the failure process of Pusa landslide by distinct element method (UDEC). The Voronoi diagram algorithm was used to discretize the rock blocks in the upper part of the mining area, and the erosion in sliding source area caused by heavy rainfall was simulated by increasing the block density and reducing the joint strength. Results obtained using UDEC matched the failure process recorded by UAV, and the subsidence of monitoring points on the slope surface was well coincident with the InSAR results. The DEM results are as follows: firstly, under the action of underground coal mining, the overlying strata of the mountain deform toward the goaf and the deformation of the stratum increase significantly with the caving of the roof stratum; and the deep karst fissures in the overlying stratum have an important influence on the deformation of the mountain; the upper strata form a subsidence zone along the fissures, expanding the range of tensile fissures. Secondly, due to the excavation and unloading of the rock masses at the leading edge of the sliding area, the extrusion deformation occurs to the outside of the slope, resulting in the critical instability of sliding area. Finally, with the strength decreasing of rock masses and structural planes by heavy rainfall, the stability of the mountain continues to decrease until the sliding area collapses.