Energy consumption analysis of the granular run-out process: effect of particle shape and slope angle

Flow-like landslides and debris flow disasters pose great threats to the human living environment. Disaster risk control largely relies on good knowledge of the mechanism of disaster evolution. To better understand debris propagation and develop a run-out model, this paper conducts a detailed analysis of the coupled effect of slope angle and particle shape based on energy consumption, which is still lacking in the literature. A series of DEM simulation tests considering five types of particle shapes are conducted. The results indicate that particle shape exerts a great influence on granular mobility, and the mobility is ranked from high to low as sphere-like particles, pyramid-like particles, slab-like particles, cube-like particles and rod-like particles. Such a particle shape effect is also dependent on the flow inertia properties, and more inertial granular flow shows a less significant particle shape effect on its mobility. Particle shape effect on granular mobility is mainly through affecting the energy loss caused by tangential collision and rolling friction, and this conclusion is independent of slope angle. In addition, we found that the lower energy loss of the granular flow surging downslope with steep terrain is also an important mechanism of its high-speed nature.