Friction behaviors and flow resistances of rock-ice avalanches

Rock-ice avalanches have high mobility and enormous destructive potential. However, the friction behaviors and flow resistance during the transition of flow regimes of the rock-ice avalanche remains an unsolved problem. Based on a series of measurements of normal, shear stress and pore water pressure at the rotating drum in a temperature-controllable laboratory, we quantify the influence of the ice content, particle size, drum velocity, and meltwater on the friction behaviors. The findings reveal that ice acts as a low-friction particle, leading to a significant reduction in frictional resistance of both particle-particle and particle-base. Furthermore, meltwater lubricates the particles and provides buoyancy, which also increases the mobility of the rock-ice avalanche. In addition, the augmentation of flow resistance is attributed to the increased particle size and drum velocity, thereby intensifying shear motion. In order to propose an unify theoretical model to calculate the flow resistance of rock-ice avalanche in various flow regimes. A heuristic model that relies on the extended dynamics theory is modified and can be well described the flow resistance of the tests involved in this paper. This study in the friction behaviors and flow resistance depending on the internal/external factors may be considered in hazard assessments of rock-ice avalanches in cold high-mountain regions.