Abstract

Abstract 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.