Discrete element analysis on granular material of flow mobility characteristics under the extraterrestrial environment: Insight from column collapse test

With the increasing interest of countries in deep space exploration, investigating the effect of space environment on the flow mobility and failure mode of granular column collapse, has a vital significance for in-situ resource utilization, base site selection, and construction. This paper employed the discrete element method (DEM) to study the influence of van der Waals force on the flow mobility and failure mode of granular column collapse. First, a complete three-dimensional contact model, considering the van der Waals force between particles, is used to study the flow mobility and failure mode of column collapse. Second, the granular column collapse tests under different van der Waals force are simulated using DEM. Finally, a contrastive analysis of van der Waals force influence on the flow mobility and failure mode of column collapse is performed. The simulation results show that, during the column collapse process, the high granular velocity gradient, the high granular rotational velocity, and the sparse contact location distribution, have a positive correlation. Three failure modes of column collapse have been identified with the van der Waals force increased, which are the diffusive type, local type, and stable type. In the failure mode of diffusive type, the van der Waals force has little influence on the granular translational and rotational velocities, the flow mobility index, the energy conversion, and the ratio of energy dissipation, however, in the failure mode of local type, with the van der Waals force increased, the granular translational and rotational velocities, the flow mobility index, the energy conversion, and the ratio of energy dissipation decrease significantly.