Multi-scale Modelling of Granular Pile Collapse by Using Material Point Method and Discrete Element Method

Granular debris flows are often observed in mountainous areas in Southwestern China. The process is accompanied with large deformation and the evident transitions between solid- and fluid-like states bring difficulties in proposing a unified phenomeno- logical constitutive model. In this study, a hierarchical multi-scale modelling scheme is developed, and is applied to simulate a granular pile collapse. The macroscopic behavior is modelled by using material point method (MPM), which is suitable for large deformation treatment, while the constitution relation at each material point is extracted from discrete element method (DEM) modelling. This MPM/DEM multi-scale modelling strategy abandons any constitutive assumptions as required in MPM, and facilitates effective cross-scale interpretation and understanding of granular flow behavior. It provides a potential approach to simulate large deformation of granular materials when their constitute relations are hard to be derived explicitly.