Analysis of the effect of rock layer structure on the toppling failure evolution of soft-hard interbedded anti-dip slopes

The soft-hard interbedded anti-dip rock slopes (SHIADRS) are unique among all layered rock slopes, as the mechanical properties of hard and soft rock layers are completely dissimilar. These slopes are abundant in south-western China. Therefore, this study examined the evolution of SHIADRS toppling failure using a centrifuge model test. The test results indicate that the entire SHIADRS failure process can be roughly divided into three stages: 1) the slight deformation stage involving tension and bending of rock layers, 2) the development stage involving tensile cracks at the slope top and the formative stage of toppling zones as well as 3) the total failure stage. Furthermore, the toppling deformation process of the SHIADRS can be divided into three stages concurrently, based on the magnitude of the displacement rate: 1) stable deformation stage, 2) unstable deformation stage, and 3) accelerated deformation stage. The universal distinct element code (UDEC) is utilised further to investigate the impact of rock layer structures on SHIADRS failure patterns. The simulation results indicate that variations in the thickness of soft and hard rock layers have no significant effect on the failure process and macroscopic failure patterns of SHIADRS. Additionally, the failure patterns of anti-dip hard rock slopes, anti-dip soft rock slopes and SHIADRSs were discussed, with SHIADRSs having the most complex failure pattern. Based on the fracture mechanics theory and the independent cantilever beam model, an improved method for calculating the stability of SHIADRS is proposed, which can determine the stability of rock layers by calculating the residual sliding force.