Application of the discrete element method for modeling of rock crack propagation and coalescence in the step-path failure mechanism.

Abstract

The present study evaluates the discrete element method (DEM) as a tool for understanding the step-path failure mechanism in fractured rock masses. Initially, the study simulates crack propagation and coalescence in biaxial and triaxial laboratory tests. The results of this analysis showthat the DEMaccurately represents these processes in comparison to other studies in the technical literature. The crack propagation and coalescence processes are important in the step-path failure mechanism for slopes. Simple examples of this mechanism were modeled, and their results were compared with those of the analytical model proposed by Jennings (1970). Among the possibilities suggested by Jennings,modelingwith DEMdid not provide a good approximation for the case of coplanar cracks, forwhich failures in the intact rock bridges should only be caused by shear forces. Inmodelingwith DEM, tensile failures occur within the sliding block, generating forces that are not considered in the Jennings model. The non-coplanar crack condition provided a better approximation, since the Jennings model formulation for this case includes the tensile failure of the rock. The main advantage of the DEM over other computational tools is its micromechanical representation of discontinuous media, which permits a better understanding of the step-path failure mechanism. However, good calibration of the macroscopic parameters of the rock and its discontinuities is necessary to obtain good results.