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Abstract

The rise in global mean temperatures induced by climate change causes accelerated permafrost degradation. In high mountain rock slopes, rock falls in permafrost areas are triggered by decreasing restraining forces such as friction loss in joints or fatigue of rock bridges, as well as increasing destabilizing forces such as hydrostatic or cryostatic pressure. Although our knowledge of the thermal influence on permafrost degradation has improved over the last decades, its mechanical effect on rock slope destabilization remains rather poorly understood. In this work, we modeled a generic mountain based on Mont fort topography (Verbier, CH) using the 3D Distinct Elements Numerical Method (3DEC software) to simulate and analyze rock failure processes. A simplified rock joint network is defined by modeling different rock joint types (water-filled-, ice-filled-rock joints, and rock joints with a high cohesion representing rock bridges). Our developed thermo-mechanical joint model simulates the main permafrost rock destabilization processes, i.e. joint strength temperature dependency and hydrostatic pressures. The process-based numerical failure analysis emphasizes the contribution of each destabilization process with respect to the fracture depth. The results show that temperature changes affect the rock stability deeper than the active layer. Overall, our results highlight the effect of the geometrical joint network configuration and the temperature influence on rock joint failure propagation. Our study advances our understanding of thermo and hydro-mechanical failure processes in permafrost rock slopes, with several potential applications in structural engineering and natural hazards.