Impact behavior of superspeed granular flow: Insights from centrifuge modeling and DEM simulation

Abstract

The impact behavior of superspeed granular flows is not sufficiently understood, although it is the basis for establishing an impact model, which is important in barrier design. Centrifuge-based modeling is a promising tool for reproducing the superspeed nature of a granular flow under a prototype stress condition. Therefore, this study established a novel centrifuge model to investigate the effect of flow speed and volume on the impact behavior of superspeed granular flows. To further verify our centrifuge modeling results and reveal more details of granular impact dynamics, a DEM-based numerical model operated under an actual centrifugal field and Coriolis field was used. The results reveal that the interparticle interaction consumed most of the granular flow energy in three ways: dead zone deformation, particle collision within the subsequent flow, and flow–dead-zone interaction, accounting for 8%, 82%, and 10%, respectively. The failure mode of the formed dead zone varied during the debris–barrier interaction, and a static failure mode is proposed to conservatively estimate the action force exerted by the dead zone. The total force on the barrier should include three main parts: the force caused by the self-weight of the dead zone, the force caused by the direct impact of granular flow after climbing on the ramp formed by the dead zone, and the force transmitted by the dead zone and generated by the interaction between the dead zone and the subsequent flow. The third part is also important because it may account for a considerable portion of the total force (the percentage may depend on the dynamic characteristics of granular flow), but is not sufficiently addressed in existing impact models. Additionally, we found that a scale model under the reduced stress condition may underestimate the impact force; therefore, centrifuge-based modeling with a passive Coriolis condition is encouraged for investigating the impact behavior of superspeed granular flows.