Application of the material point method (MPM) to characterise the impact forces of granular landslides on rigid obstacles

Abstract

This study deploys the Material Point Method (MPM) to investigate the soil pressures exerted on a 3D rigid obstacle partially obstructing a dry granular flow; a configuration not previously addressed in the literature on a numerical modelling basis. A 2D simulation is first developed and validated against a flume experiment that monitors the interaction of dry granular flows with retaining structures under varying flume angles. The model is then extended to 3D, enabling the adjustment of the obstacle's geometry to observe the impact of granular flows on impermeable rigid obstacles partially obstructing the soil material. The trend in the recorded soil forces exhibits an initial peak that occurs simultaneously with the first impact, followed by a steep degradation branch as the soil deposits in front of the structure, thus reducing the flow's dynamics. The numerical simulation is subsequently upscaled to ensure that macroscopic dimensional analysis adequately interprets small-scale numerical observations to mimic prototype conditions using the MPM approach. Simplified factors are finally derived to represent the response characteristics of large-scale simulations based on the original findings.