Wave erosion induced bank collapse and its impact on landslides: insights from model tests

Wave erosion along the hydro-fluctuation zone is a pervasive phenomenon in the Three Gorges Reservoir Area (TGRA), culminating in bank collapse and consequent initiation of landslide events. To investigate the evolution process and failure mechanism of “wave erosion - bank collapse - landslide movement”, field investigations on TGRA are first carried out to identify the main features of the wave erosion. A reservoir landslide model test platform was subsequently designed that can control the water level of reservoirs, regulate wave patterns, and simulate various bedrock shapes. A material ratio scheme that accounts for the “sliding mass partition similarity” is proposed, along with a novel method for simulating sliding surface materials using composite geotextile and lubricating oil. A series of physical model tests were conducted to simulate the process of wave erosion, bank collapse, and subsequent landslide movement. The erosion evolution of the landslide front, variations in earth pressure, and the overall deformation of the landslide are monitored during the tests. The key findings are as follows: (1) Based on the proposed sliding mass material ratio scheme, novel sliding band materials and self-developed test device, the “wave erosion - bank collapse - landslide movement” process of wave erosion-induced landslides is successfully reproduced. (2) When the landslide front was steep, the wave erosion rate was higher. Over time, the slope of landslide front gradually became gentler, leading to a reduction in the wave erosion rate, which can be described by an exponential decay function. (3) The decrease in anti-sliding force due to erosion-induced bank collapse is the primary factor affecting the stability coefficient of the landslide. Additionally, the unloading effect of the bank collapse weakens the mechanical properties of the soil, significantly reducing its shear strength compared to natural conditions. This study offers a scientific basis for landslide prevention and mitigation strategies in the TGRA. • The process of “wave erosion - bank collapse - landslide movement” was simulated. • The erosion rate of bank slope shows exponential decay over time. • The mechanism of wave erosion and bank collapse affecting landslide stability was revealed. • The unloading action of bank collapse reduces the shear strength parameters of soil.