Micro-mechanism of basal stresses in steady rock-ice mixture flows: Insights from 2D DEM simulations

Abstract

Rock-ice avalanches developing in high-altitude and cold regions typically result in massive destruction due to their exceptionally high impact force and long run-out distance. Comprehensively analyzing the basal stresses generated by this granular process is essential for understanding mechanical behaviors such as erosion and entrainment. However, the current understanding of the basal stresses generated by rock-ice mixture flows remains incomplete. In this paper, a series of miniature 2D steady flows of spherical rock-ice particles on a bumpy subsurface were conducted using DEM to provide physical insights for hazard risk management. Simulation results indicate that the kinetic energy of rock-ice mixture flows reach a steady state after the segregation reaches a stable state along the depth direction. The probability density functions of basal stresses exhibit Gaussian-like distributions in the simulations, suggesting that the interactions between rock-ice particles and the base are characterized as identical and independent events. Positive correlations exist between normalized stress fluctuations (the maximum and standard deviation of stress) and the ice content. Additionally, normalized stress fluctuations exhibit positive correlations with the free volume per spherical particle (a metric for quantitatively characterizing the free space surrounding spherical particles, which in turn influences the random particle motion) and the modified granular temperature, which includes both translational and rotational components. This highlights the significance of granular thermal motion in rock-ice mixture flows.