Research on the creep mechanism of Huangniba landslide in the Three Gorges Reservoir Area of China considering the seepage–stress coupling effect

The impoundment of China’s Three Gorges Reservoir has led to the revival of many old landslides along the bank, and the annual fluctuation in water level of 30 m is likely to affect the creep deformation of these landslides. Through a field investigation of Huangniba landslide in the Three Gorges Reservoir Area, the local deformation signs and field monitoring data were analyzed. It was preliminarily considered that this landslide was currently at the creep stage and the creep rate was affected by the reservoir level variation. In order to carry out further research on the effect of reservoir level variation on the landslide movement, the finite element method was used to establish the seepage–stress coupling model of Huangniba landslide based on the seepage–stress coupling theory and taking into account the creep behavior of landslide material. The model was used to simulate the variation characteristics of the seepage field, stress field, and displacement field in the landslide during 6 years of cycles of reservoir level variation. Based on the numerical simulation results and field monitoring data, the deformation mechanism of the landslide was discussed. Finally, the sensitivity of the parameters in the creep model to the simulation results was discussed. The results show that creep deformation is the main deformation mechanism of Huangniba landslide, and it is obviously affected by the drawdown of the reservoir water level. During drawdown of the reservoir level, the pore water pressure inside the landslide decreases, resulting in an increase in effective creep stress and creep strain rate, thus accelerating creep deformation. The results of this study will provide a reference for the deformation mechanism of such creeping landslides subjecting to reservoir water level fluctuation.