Influence of size and cross-section shape on granular column collapses

Abstract:

Granular materials are ubiquitous in nature and engineering practices. The collapse of granular columns is commonly used as a benchmark study to better understand the flowing behavior and deposition morphology of geophysical flows, such as debris flows and landslides. Breakthroughs have been made to explore the relationship between the run-out behavior and the initial and boundary conditions of the granular column collapses. Meanwhile, size-effects have been witnessed to change column collapse behaviors, yet no literature has been investigated thoroughly on this topic. Additionally, cross-section shapes, as an important initial condition, could also influence the evolution of the front line of granular flows and the deposition morphology of a collapsed granular column. In this study, we utilize the discrete element method (DEM) with Voronoi-based spheropolyhedron particles to investigate the run-out behavior and the deposition morphology of the collapse of granular columns with different sizes and cross-sections. We linked the size effect that occurred in granular column collapse problems to the finite-size scaling functions. The collapsing behavior of granular columns with different cross-section shapes is also studied. We try to describe the spread of granular columns during the granular column collapse and the transport of materials with a modified Exner equation, which is originally for describing the delta formation in a geomorphic problem. We believe that such a study is crucial for us to better understand how granular material flows, how it deposits, and how to consider the size effect in the rheology of granular flows.