Centrifugal model test of deformation law under different reservoir water fluctuation rates: Muyubao landslide case study

Many ancient landslides have become active due to the impoundment of the Three Gorges Reservoir. Considering the Muyubao landslide in the Three Gorges Reservoir area as the research object, we analyzed the long-term deformation law since the impoundment of the reservoir and conducted centrifugal model tests of the landslide deformation process under different reservoir water fluctuation rates. The monitoring data analysis reveals that the deformation of the Muyubao landslide is mainly affected by the elevation of the reservoir water level and its rising and falling rate. A deformation greater than 30 mm mainly occurs at the water level of 165–175 m. A higher reservoir water rising rate promotes landslide deformation, with a monthly cumulative displacement of above 30 mm in the reservoir water rising stage. Further, a lower reservoir water decline rate can promote several landslide deformation events with monthly cumulative displacement greater than 30 mm. A Centrifugal model test demonstrates the Muyubao landslide deformation to the hydrodynamic buoyancy pressure of reservoir water. The head difference inside and outside the slope is minimal when the reservoir water rising and the falling rate is small, and the reservoir water buoyancy controls the deformation of landslides. However, the head difference inside and outside the slope increases with the reservoir water rise and fall rate, leading to increased hydrodynamic pressure, which weakens the landslide deformation in the reservoir water rising stage, and strengthens the deformation in the reservoir water-falling stage. The results provide a significant reference for landslide control and reservoir operation optimization in the Three Gorges Reservoir area.