Estimating the maximum impact force of dry granular flow based on pileup characteristics

The maximum normal impact resultant force (NIRF) is usually regarded as the sum of the static earth pressure of the dead zone and the dynamic impact pressure of the flowing layer. The influence of the interaction between the flowing layer and dead zone on the impact force is ignored. In this study, we classified two impact models with respect to the pileup characteristics of the dead zone. Then, we employed the discrete element method to investigate the influences of the pileup characteristics on the impact force of dry granular flow on a tilted rigid wall. If the final pileup height is equal to the critical value, the maximum NIRF can be estimated using a hydrostatic model, because the main contribution to the maximum NIRF is the static earth pressure of the dead zone. If the final pileup height is less than the critical value, however, the particles in the dead zone are squeezed along the slope surface by the impact of the flowing layer on the dead zone, and because of shear effects, the flowing layer causes an entrainment in the dead zone. This results in a decrease in the volume of the dead zone at the moment of maximum NIRF with increases in the slope angle. As such, the maximum NIRF mainly comprises the instant impact force of the flowing layer, so hydro-dynamic models are effective for estimating the maximum NIRF. Impact models will benefit from further study of the components and distribution of the impact force of dry granular flow.