Incorporating particle roughness and hardness into contact model to reproduce elastic behaviors of granular soils in DEM

Abstract

In this work, we present a physically-based contact model incorporating particle roughness and hardness to accurately capture the inter-particle interactions of common geomaterials in DEM based on extensive micromechanical testing results. Specifically, in the contact normal direction, unlike the ideal Hertzian model, the particle roughness-embedded contact model is adopted to characterize the plastic deformation of particle asperities exclusively. In the tangential direction, the traditional MD model is modified with a precise critical slip displacement, enabling a more accurate description of the nonlinear relationship between tangential force and slip displacement. Based on this new contact model, we further calibrate the model parameters for diverse geomaterials, which are rather helpful for future quantitative DEM simulations. Finally, a series of drained triaxial simulations are conducted on uniformly graded spheres to explore the effects of model parameters on the evolution of elastic stiffness with the shear strain, which provides important implications for the elastic behaviors of a variety of geomaterials. Furthermore, the underlying micromechanical processes, particularly those related to the statistics of contact normal and tangential stiffness, which are challenging to access in indoor tests, have been elucidated. This study lays a solid foundation for the future advancement of DEM in the geomechanics community.