Centrifuge and DEM investigation of dry granular impacts: Effect of granular volume under high-speed impact conditions

Large-scale high-speed granular avalanches can be catastrophic; however, small-scale model tests cannot reproduce the high-speed impact effect, resulting in barrier designs lacking detailed knowledge considering the prototypical dynamic conditions of granular avalanches (e.g., high moving velocities and varied material volumes). In this paper, a well-designed centrifuge model is adopted to reproduce high-speed granular avalanches with variable flow velocities and material volumes, and a calibrated DEM model is also used to offer further insights. The results indicate that under high-speed impact conditions, the effect of granular volume on the pressure distribution pattern dominates, but its influence on the impact loading rate is less obvious. To estimate the high-speed impact force, a constant pressure coefficient of 1 can provide a reasonable estimation for the dynamic component if boulder impacts are excluded, and the static component can be calculated using the weight of the dead zone based on the assumption of a static state of the dead zone. In addition, considering the transition of the impact pressure distribution model caused by different granular volumes and flow velocities, a rectangular pressure profile is suggested for barrier design against high-speed dry granular avalanches when the peak total impact force is adopted as the design load.