Experimental Study on the Thermo-Hydro-Mechanical Coupling and Abrupt Initiation ofRock-Ice Avalanches via Centrifuge Modeling

Climate change has significantly increased the frequency of rock-ice avalanches in alpine regions, yet their remote locations and abrupt nature have long hindered a deep understanding of their initiation mechanisms. This study investigates the mechanical and hydraulic processes triggering rock-wedge and rock-wedge-ice slides through advanced geotechnical centrifuge experiments (130-g), drawing insights from the 2000 Yigong landslide and the 2021 Chamoli rock-ice avalanche. By simulating freeze-thaw cycles (FTCs) in a temperature-controlled environment, we conducted comparative analyses between rock wedge models with and without glacier cover. The results demonstrate that frost heave and pore water pressure fluctuate parabolically with temperature, leading to progressive rock mass softening and stress redistribution. Notably, meltwater infiltration in the glacier-covered models significantly accelerated the failure process, by weakening the rock-ice bonding and increasing pore pressure along discontinuities. The experiments reveal that the transition from observable surface deformation to catastrophic failure occurs extremely rapidly, often in less than 20 seconds. These findings provide critical experimental evidence of thermo-hydro-mechanical coupling in high-altitude cryosphere hazards and identify high-amplitude fluctuations in stress and pore pressure as vital precursors for early warning and risk mitigation.