Abstract: To investigate the deformation and evolution mechanism of landslides under changing reservoir water levels, a 1∶70 scale model of the Cheyiping landslide was established, and a reservoir water level rising and falling system was designed. Centrifugal model tests were conducted with one water level rise and two consecutive water level plummets at different rates. The findings reveal that during the water level rising stage, the landslide deformation is not significant. However, during the initial water level drop, tension cracks in the front edge of the landslide develop rapidly and form a fracture zone. Subsequently, the fault zone collapses and tension cracks appear in the middle and rear part of the landslide. During the second water level drop, the landslide continues to slide along the original fracture zone, but the sliding noticeably attenuates. The vertical compaction in the middle and rear parts of the landslide leads to the stabilization of fracture propagation. During the water level rising stage, the pore pressure exhibits noticeable lag and gradually diminishes in subsequent stages. The soil pressure in the leading edge of the sliding mass varies significantly in each stage, while in the middle and rear changes most severely during the first rapid water level drop. Overall, the water level drop rates that lead to landslide instability range from 0.7 to 1.5 m/day. The dynamic water pressure effect is stronger in the deeper parts of the landslide compared to that in the shallower layers. The deformation of the landslide is more influenced by the initial water level plummet than the second. The deformation and failure gradually decrease from the front to the rear, resembling traction characteristics.The water level rising, the first plummeting and the second plummeting stages demonstrate initial deformation, accelerated deformation, and decelerated deformation characteristics, respectively.

Key words: reservoir bank landslide, hydrodynamic pressure, deformation, plummeting water level, centrifugal model test