Background In order to study the dynamic mechanism of bank stability under the condition of rainfall combined with water level fluctuation, a reasonable ecological slope protection scheme was designed.

Methods In this study, the combination of field investigation, mechanical test and numerical simulation was used to reveal the characteristics of the slope stability changing with water level and the failure mechanism of the slope in the Beibei section of the Jialing River, and the key technical parameters of the "living wood pile slope protection" measures were discussed by comparing with traditional plant slope protection methods and engineering pile slope protection methods.

Results 1) The stability of the river bank beach slope fluctuated with the rise and fall of water level, and the slope stability dropped rapidly during the water level fluctuation stage. The reason is that the external hydrostatic pressure of the slope unloaded with the rise and fall of water level, and the seepage pressure inside the slope pointing outward from the slope caused shallow damage to the middle slope. In summer and autumn, when the water level of the river dropped more than 3 m/d, the early warning of landslide disaster on the river bank and beach should be triggered. 2) When the live wood pile, pile diameter and pile angle were fixed, properly increasing the pile length and reducing the pile spacing will help limit the horizontal displacement of the slope. It was suggested that the pile configuration of the gentle slope of the river bank beach was the middle upper part between the warning water level and the normal water level, with the pile spacing D=2.3 m, pile length L=3.3 m. The stability of topsoil will be affected only when the pile length was closed to the potential sliding layer. 3) At the initial stage of the configuration of live wood piles under the optimized parameter configuration, the stability coefficient increased by 18.6% under the extreme conditions of water level fluctuation, which was 3.8 times of the effect of traditional grass and shrubs on slope consolidation. After the root system of wood piles was fully grown, the slope stability coefficient increased by 22.3%, which was 3.7% more than that of piles configured with the same configuration.

Conclusions This paper studied the change of pore water pressure of bank slope under the conditions of rainfall and water level fluctuation, and compared the slope stability of different support measures of bank slope in the Jialing River section of the Three Gorges Reservoir. On this basis, the arrangement parameters of movable wooden piles were optimized to provide theoretical basis and technical support for the ecological protection of the riverside in the Three Gorges Reservoir area.