Quantifying the impact of dry debris flow against a rigid barrier by DEM analyses

This study investigates the interaction between dry debris flows and a rigid barrier through discrete element modeling (DEM) of flume tests. The debris materials were modeled as an assembly of loosely packed spherical particles and the rigid barrier was represented by a layer of fixed particles. The numerical model was validated by comparing the numerical results with the experimental data reported in the literature, in terms of the debris flow morphology and evolution of impact forces acting on the rigid barrier. This model was further employed to examine the influence of barrier slope on the debris-barrier interactions. Based on the numerical results, three interaction stages were identified, namely the frontal impact, run-up and pile-up. The maximum impact force measured in this study exhibits a power law dependence on the barrier slope. In addition, during the impact process, the majority of initial total energy was dissipated by particle-particle and particle-flume interactions, while only a negligibly small amount of energy was dissipated by particle-barrier interaction. The numerical results also indicate that long spreading debris flows are very effective in facilitating energy dissipation, diminishing the impact force acting on the rigid barrier. These considerations can finally contribute to the design of effective debris flow barriers.