Slow-moving rock slopes undergoing long-term deformation may experience irreversible acceleration driven by groundwater level variations. Such hydrological forcing is typically induced by seasonal rainfall or glacial melt, which modifies local effective stress states along pre-existing shear surfaces. Under sustained sub-critical stress, the rock slope accumulates hydromechanical damage over time, ultimately leading to rapid landslides. The complexities in hydromechanical coupling and fatigue damage accumulation challenge numerical and experimental tests.
We propose a novel time- and stress-dependent hydromechanical damage model to simulate nonlinear displacement in slow-moving rockslides. We first verify this model via laboratory scale creep tests. The reproduced complete creep curve involves attenuation, steady and accelerated creep stages, which represent different phases in slow-to-fast transition for a long-term landslide. Then, we conduct a case study of long-term slow-moving landslides in the Alps, where cyclic precipitation and meltwater-induced aquifer level variations affect local effective stress. The simulation reveals that damage accumulation accelerates during pore pressure rise phases, manifesting as pulsed slip acceleration events. Cyclic aquifer level changes promote localized crack extension, enhancing regional permeability and expanding the zone influenced by hydro-mechanical damage. Repeated cycles ultimately drive uncontrolled acceleration in sliding velocity.
 

landslide,fatigue damage,Hydromechanical coupling,fracture propagation,Discrete Element Modelling