Abstract: Many landslides along the bank have reactivated after the impoundment in the Three Gorges Reservoir Area (TGRA). In order to study the landslide deformation characteristic subjected to fluctuation of reservoir water level, a large-scale centrifuge test model was designed based on typical landslide with rectilinear sliding surface in TGRA. The deformation images, the curves of pore water pressure (PWP) and earth pressure (EP) vs. time were obtained by high-speed cameras and pore water pressure and soil pressure sensors during the modelling of two cycles of reservoir fluctuation. The results could be summarized as follows: in the initial stage of the water level drawdown, the PWP and EP gradually decreased. When the water level fell for 15 minutes, the frontal body pull apart and down, the middle and rear parts of the landslide had a creep movement and compaction process dominated by vertical displacement, and the deformation stopped two minutes after the water level stopped falling. When the reservoir drawdown again, the frontal part slid along the original fracture zone, and no obvious deformation occurred in the middle or rear parts. In addition, when the reservoir water infiltrated into the landslide for the first time, the PWP in the slope lag behind the water level obviously, whereas the lag effect had diminished during the next time. The landslide is greatly affected by the hydrodynamic pressure of reservoir drawdown and its deformation has a retrogressive characteristic. The creep compaction behavior improved the stability of the middle and rear parts of the landslide gradually. Therefore, no deformation occurred during the water storage later, and the experimental phenomena coincide with the deformation characteristics of actual reservoir landslide. It reveals the deformation mode and evolution trend of the landslide in TGRA subjected to reservoir fluctuation, which provides a basis for the geohazard prevention.

Key words: Three Gorges Reservoir, reservoir landslide, centrifugal model test, reservoir fluctuation, landslide evolution