Ice content dependence of fluctuating basal forces in rock–ice avalanche: From numerical rotating drum tests

In this study, we investigated ice content effects on basal force fluctuations in rock-ice avalanches using discrete element method (DEM) rotating drum simulations. Calibrated DEM parameters reproduced experimental benchmarks, enabling numerical tests across ice contents (0–100%). Our results demonstrated ice-driven phase segregation: Low-density ice particles migrate to flow fronts, while gravel accumulates in tails. Increasing ice content linearly reduced the mean basal force, extreme force, and force standard deviation, attributed to ice's friction reduction and lubrication effects. Statistical analysis revealed that basal force fluctuations followed the Generalized Pareto Distributions, with heavier tails under low ice content indicating heightened stochasticity. Normal and shear stress fluctuations exhibited power-law correlations with solid inertial stress, confirming that collisional interactions dominated force variability. Ice-mediated lubrication diminished interparticle locking, promoting collision-driven momentum transfer and altering rheological behavior. These findings elucidate mechanisms linking ice content to segregation and basal forces, offering theoretical insights for modeling rock-ice avalanche hazards.