Coupled MPM/DEM multiscale modelling geotechnical problems involving large deformation

Accurate modeling of many geotechnical problems needs the consideration of large deformation soil behavior. The Material Point Method (MPM) has gained increasing popularity over many other conventional numerical methods such as Finite Element Method (FEM) in continuum modeling of large deformation problems. In this study, we present a novel coupling scheme combining MPM and DEM (Discrete Element Method) for multiscale modeling of large deformation geomechanics problems. A computational multiscale scheme based on hierarchical coupling of MPM and DEM is proposed, based on the similar concept of FEM-DEM coupling proposed previously by the authors (Guo and Zhao, 2014, 2016a, 2016b). In this scheme, the MPM is employed to treat a typical boundary value problem in geotechnical problem that may experience large deformations, and the DEM is used to derive the nonlinear material response required by MPM for each of its material points. The proposed coupling framework helps avoid phenomenological constitutive assumptions in typical MPM, while inherits its advantageous features in tackling large deformation problems over the use of FEM (e.g., no need for re-meshing to avoid highly distorted mesh in FEM). It offers the capability of direct micro-macro linking for us to understand complicated behavioral changes of granular media over all deformation levels, from the initial elastic stage en route to the large deformation regime before failure. Demonstrative examples, including the cyclic loading of granular media and the footing foundation problem, are shown to highlight the advantages of the new MPM-DEM framework.