A discrete element method-based simulation of block-flexural toppling failure

Stability assessments of block-flexural toppling failure using limit equilibrium methods are significantly affected by the assumption of a single overall failure surface, and the joint configuration and discontinuity persistence can affect the prior assumption of the overall failure surface used in limit equilibrium methods. In this study, a particle-based discrete element method (DEM) is used to assess the stability of rock slopes with the potential for toppling failure. The DEM is used to simulate block-flexural toppling failure based on an experimental tilting table. A validated numerical method is then developed to investigate the stability of block-flexural toppling failure-prone slopes. The results demonstrate that the calibrated DEM can successfully simulate the toppling failure of blocks prone to this failure mode. The presence of complex joint distributions in the model highlights that a single overall failure surface is not necessarily a reliable assumption in theoretical models of block-flexural toppling failure. In a slope with different cross-joint sets, two failure surfaces were observed. The results indicate that the spacing and friction angle of the main joint set and the joint configuration significantly influence the overall failure plane, slope deformation patterns and slope stability in block-flexural toppling failure-prone slopes. Furthermore, the identified stable, toppling and sliding regions in a slope undergoing block-flexural toppling failure were affected when the joint persistence was changed. Overall, this study highlights the assumption of a single failure surface used in the limit equilibrium method is not necessarily valid for block-flexural toppling failures.