Static and dynamic impact forces on a rigid barrier due to dry debris flow simulated by a DEM-based granular column collapse

Abstract

Geophysical flows like debris flows require protective barriers so as to scale down their disastrous effects. The impact force exerted on these barriers depends upon several factors like the velocity and height of flowing debris, the density and other associated characteristics of flowing mass, and the height of the sediment deposited behind the barrier. These factors are found to vary with time during the debris flow process, thereby causing significant temporal variations in the magnitude of impact force. Assessing the impact force on a barrier is a prerequisite for its design. In this work, the impact of dry debris flow, emanating from a granular column collapse, on a rigid barrier has been investigated using 3-D Discrete Element Method (DEM). It has been found that the impact force is predominantly influenced by dynamic thrust at the initial stages, which, with elapse time, subsequently transits to the sole contribution of static pressure. The applicability of the existing hydraulic models comprising hydrostatic and hydrodynamic formulae has also been analysed in this exercise. Furthermore, the empirical coefficients associated with these formulae have been evaluated for the dry debris flow impacting the rigid barrier.