Combined Inter-Particle and Wall-Particle Friction Coefficient Effects on Collapse Mobility and Deposition Morphology of a Granular Column Composed of Pentagonal Grains

Abstract

Frictional gravity-driven granular flows are ubiquitous scenarios in natural hazardous events such as landslides, rock avalanches, and snow avalanches. Understanding the physical behavior of the natural hazards above may play an important role in mitigating and controlling their potential impacts. The boundary-particle and inter-particle friction coefficient may strongly govern the mobility and runout distance of such flows. In this paper, we numerically explore these frictional effects on the kinetic energy and deposition morphology of a pentagonal granular column collapses on a horizontal plane utilizing discrete element simulations. The results showed that small values of both wall-particle and inter-particle friction coefficients significantly affect the mobility and deposition of granular materials. In contrast, these physical behaviors are nearly insensitive with large values of both friction coefficients. Interestingly, by proposing a dimensionless parameter under inversely linear combining the wall-particle friction and inter-particle friction coefficient, both kinetic energy and deposition morphology are nontrivially controlled but with different values of the weighting factor of the inter-particle friction coefficient. This interesting finding confirms the different contributions of wall-particle and inter-particle friction coefficients and may originate from the contact forces network, characterized by the probability density functions of normal contact forces in the collapsing and spreading stages. These observations may significantly provide a better understanding of the behavior of frictional hazardous flows, leading to the development of effective strategies for risk reduction.