How Ice Particles Increase Mobility of Rock‐Ice Avalanches: Insights From Chute Flows Simulation of Granular Rock‐Ice Mixtures by Discrete Element Method

Abstract Rock‐ice avalanches occurring in cold high‐mountain regions often cause catastrophic damages due to their extremely high mobility. Rock and ice have different physical properties, such as particle size, density, friction, etc., leading to the segregation of rock and ice in the mixture and impacting its mobility. However, how ice affects the mobility of rock‐ice avalanches is still poorly understood. A series of numerical experiments were conducted by using the discrete element method to quantify the effect of rock‐ice particle size ratio and ice content on the particle segregation and mobility of their mixtures. Results show that rock‐ice particle size ratio and volumetric ice content determine the spatial distribution of ice, thereafter affecting the mobility of the rock‐ice mixture by controlling the ratio of particle collision stress and coulomb friction stress. In particular, different from conventional understanding, the ice spatial distribution can have a significantly greater influence on the mixture's mobility compared to the volumetric ice content in some scenarios. This study provides insights into the effect of granular ice on the mobility law in the early phase of rock‐ice avalanches and has important implications for their hazard assessment.