The Friction Behavior of Rock-Ice Avalanches in Relation to Rock-Ice Segregation: Insights From Flume Physical Experiments

Rock-ice avalanches in cold-high mountainous regions exhibit remarkably high mobility, frequently resulting in catastrophic consequences. However, the systematic influence of ice on the mobility of rock-ice avalanches remains poorly understood. This paper addresses this gap by conducting a comprehensive flume experiment in a temperature-controlled room at −10°C, simulating rock-ice avalanches and considering variations in rock-ice particle size ratios and ice contents. Overall mobility and segregation patterns are quantified by analyzing deposition characteristics, while high-speed cameras capture velocity and segregation features during motion. Our investigation reveals a notable rock-ice segregation phenomenon that significantly impacts the mobility of the mixture. Building on insights from prior numerical experiments conducted under nearly-no-base-slip conditions (Feng et al., 2023, https://doi.org/10.1029/2023jf007115), our results underscore that the particle segregation simultaneously influences both internal (bulk) and basal frictions, thereby producing different nonlinear impacts on the mobility of the rock-ice flow. Additionally, an empirical formula is proposed to describe the evolution of the friction coefficient in cases with different rock-ice particle size ratios and ice contents. These findings have significant implications for predicting runout and assessing the risk of rock-ice avalanches.