Application of the Discrete Element Method for Modelling the Block and Flexural Toppling Mechanisms in Rock Slopes

The toppling failure mode is a mechanical process in rock slopes with regularly spaced layers or foliation, which involves block overturning and bending of columnar structures. As those processes develop, the failing of internal structures in the slope may occur, leading the whole system to its collapse. The Discrete Element Method based on circular discrete elements was used to analyze two modes of toppling: the block and flexure toppling modes. The method of the study was structured by means of a progressive modelling of the phenomena, and the subsequent validation of the results through a comparison with analytical and semi-analytical approaches. The strain and strength of rock structures subjected to bending process were modeled using a new contact model between every discrete element, which resulted in a better response than other conventional contact models. Subsequently, in the numerical simulation of a physical model, the strains and strength behavior of the experimental slope are reproduced by the numerical calibration of the rock and the joint mechanical properties. The result of this process shows a significant dependence on the stiffness and frictional joint components rather than the properties of the rock itself. That was a different but an acceptable conclusion among other similar works, which aim the rock properties and the joint frictional angle the main factors that control the slope stability in toppling process.