Micromechanical investigation of particle shape effects on dry granular flow interaction with mitigation structures

Assessing the impact forces exerted by dry granular flows on protective structures is crucial for risk evaluation and engineering design against landslides. This study employs the Discrete Element Method (DEM) to numerically model granular flow interactions against a rigid barrier (Case I) and slit dams with basal undulations (Case 11), using two different geometries. The model is initially validated with spherical particles against already reported data and then extended to analyze the influence of particle shape on impact dynamics, incorporating regular dodecahedral and octahedral particles. In Case I, peak and residual impact forces on the rigid barrier remain relatively unchanged due to the absence of overflow, with impact forces decreasing as the true sphericity of particles (ψ) decreases. On the other hand, in Case II, peak impact forces on the slit dams exceed residual forces for all particle shapes due to particle overflow. Additionally, a decreasing trend in peak impact force while an increasing trend in residual impact force are observed with decreasing ψ. A similar pattern is noted in the dynamic pressure coefficient (kd) for both of the cases. These findings provide critical insights into the macro-scale behaviour of granular mass flows, linking microscale particle interactions to the improved design and efficiency of geophysical mass flow barriers.