A cohesive discrete element based approach to characterizing the shear behavior of cohesive soil and clay-infilled rock joints

Abstract

The mechanical behaviour of the infilled rock joints is highly concerned in rock joint studies due to its involvement in a wide range of mining collapses. In this study, a new cohesive constitutive model was employed and used in discrete element method (DEM) simulation to analyse the failure mechanism of infilled rock joints numerically. The exponential softening responses of the model in mixed mode loading conditions allow more realistic modelling of clay-infilled rock joints, which is more phenomenologically promising than the use of the current constitutive models in PFC2D such as the parallel bond model (PBM). The proposed model is implemented in DEM commercial codes (PFC2D) as a user-defined contact constitutive model. In parallel with this theoretical development, experimental works on shear behaviour of infilled materials and infilled rock joints under different normal loads are also carried out for the calibration of the cohesive model, and validation of the DEM based approach, respectively. Simulation results show excellent agreement with experimental counterparts demonstrating the effectiveness of the proposed cohesive model in reproducing the shear properties of clay-infilled rock joint. The proposed cohesive DEM framework, therefore, will facilitate better understanding of the shear mechanism of cohesive infilled rock joints.