Numerical simulation of wedge failure of rock slopes using three-dimensional discontinuous deformation analysis

As one of the most common failure forms of discontinuity-controlled rock slopes, wedge failure is likely to occur in a wide range of geologic and geometric conditions. In this study, the wedge failure of rock slopes and the movement and disaster processes after failure are investigated using 3D discontinuous deformation analysis (DDA). Compared with the analytical solutions derived from a typical rock wedge model, the performance of the original 3D DDA for analyzing the wedge stability under different geometrical and physical parameters is presented. The deficiency of the joint contact model in 3D DDA under critical state is improved. The improved 3D DDA is used to simulate a rock slope subjected to wedge failure in Tibet Autonomous Region, and the failure of the dangerous rock masses and movement of the formed blocks under different discontinuity cutting are discussed. The improved 3D DDA has high accuracy in calculating wedge critical stability and sliding after failure. The actual wedge slope presents sliding failure along the intersection line of structural planes, and tensile and shear failure and downward dislocations can be observed among blocks. The lateral deviation and deflection of wedge blocks occur constantly, showing 3D kinematic characteristics. With the increase of secondary discontinuities, the influence range of sub-blocks due to wedge failure becomes larger, constituting the geological disaster of the G318 national road. 3D DDA can evaluate wedge stability and analyze kinematic characteristics of wedge blocks, which lay a foundation for formulating disaster prevention countermeasures and reducing human casualties.