Influences of deposition upslope the barrier on the dynamic impact of dry granular flow

Abstract

The destructive granular flow hazards can be mitigated by intercepting the solid particles using protective barrier in the flow paths. Changes in the performance of barrier are usually observed in this process due to deposition occurring behind the barrier. However, there is a limited understanding about the effect of deposition on the dynamic impact of subsequent flows due to a complex process that involves the flow redirection and deposition entrainment by subsequent incoming flow. We investigate the dynamics of flow-barrier interaction by conducting flume tests with different deposition heights h0 normalized by barrier height H and flume inclination angles α. The impact of pileup flows and jet-like runup flows on barrier with deposition shows different flow features and barrier responses and is governed by the deposition height. An increasing normalized deposition height h0/H can mitigate barrier load and flow basal stress due to buffering effect of deposition by enhancing energy dissipation during impact. A depth-averaged analytical model is developed to estimate the changes in flow velocity and flow depth for different flow regimes (pileup/jet-like runup) impacting the barrier with deposition, considering the entrainment of deposition by incoming flow. Experimental results indicate that the proposed models are more reliable in estimating granular flow impact force compared to traditional analytical impact models that neglect the changes of flow velocity and flow depth by deposition.