A numerical study of the toppling failure of an anti-dip layered rock slope based on a cohesive crack model

The toppling failure mechanism of an anti-dip layered rock slope is a kind of common geological hazard. In order to explore the toppling failure mechanism of an anti-dip layered rock slope and the influence of interlayer shear strength and rock thickness on the failure characteristics under the condition of excavation, based on the continuous-discrete method, the finite element cohesive crack model (Cohesive Crack Model, CCM) is established by ABAQUS. Through parameter calibration and comparison, the CCM of an anti-dip layered rock slope is established, and the slope toppling failure is induced by excavation and weight increase. The numerical results are basically consistent with the centrifugal model test results that are based on the toppling deformable body in front of the dam of Gushui Hydropower Station, which verifies the correctness of the CCM. Furthermore, the failure evolution process and stress distribution characteristics of the anti-dip layered rock slope are studied, and the influence of inter laminar shear strength on the toppling failure characteristics of the slope is discussed. The results show that the front edge of the slope is partially broken at first, and obvious tensile cracks appear at the back edge, and the anti-dip rock layer breaks from bottom to top until the middle of the dumping body (first-order fracture surface), and then the surface layer of the front edge of the slope is extruded to form a second-order fracture surface. The last first-order fracture surface extends to the back edge of the slope to form a connected macroscopic fracture surface, the second-order fracture surface extends to the middle of the slope, and the slope is completely toppled and destroyed. The fracture surface basically develops along the position of the peak value of the interlayer normal stress and the inter laminar shear strength has a significant influence on the toppling failure characteristics of the slope. With the increase of the inter laminar shear strength, the initial breaking position of the rock layer become lower, the collapse range decreases gradually, and the angle of the fracture surface increases. With the increase of the layer thickness of the slope, the distribution of the first-order fracture surface deepens, the range of the collapse area increases, and the integrity of the slope slip is enhanced. The research results provide an effective calculation method and basis for the analysis and monitoring of the toppling failure of reverse-dip layered rock slopes and provide some references for the prevention and control of such landslide disasters.