The effect of the front inclination on the impact forces transmitted by granular flows to rigid structures

The assessment of the damage of existing structures caused by flow landslides, as well as the design of sheltering structures, requires the evaluation of the forces arising during the impact. In particular, the peak force depends on several factors such as the impact velocity, the material bulk density, the flow thickness, and the material compressibility. The effect of the front shape on the force evolution has rarely been taken into account because it is experimentally very difficult to consider. The aim of this paper is to study numerically the impact process evaluating the effect of the material constitutive parameters and shape of the flow front. Large deformations of the granular material are simulated by employing a 3D numerical approach based on the Material Point Method (MPM). The granular material mechanical behavior is simulated by means of an elastic perfectly plastic model with a Mohr-Coulomb failure criterion. The soil mass is initially positioned in front of the wall with a prescribed uniform velocity and the evolution of the impact force is monitored. The results show that the front shape not only influences the peak pressure, but also the evolution of the impact force with time.