Abstract: In order to study the impact of reservoir water level fluctuation on stability of landslide with weak layers, we carry out model test and measure the variations of soil pressure and pore water pressure as well as displacements of certain parts of the landslide body during reservoir water level fluctuation. Results show that as reservoir water level rises, slip resistance decreases due to immersion of reservoir water, stability of the landslide reduces, and displacement occurs in landslide. Impacts of reservoir water rising on landslide stability can be divided into three stages: stability phase, slow deformation phase and global glide phase. The three stages exhibits different characteristics, reflecting that the landslide stability decreases with reservoir water rising. Meanwhile, weak interlayer in the landslide is not only the weak part of the landslide, but also the crucial part for landslide stability.

Key words: weak interlayer, fluctuation of reservoir water level , model test, stability, soil pressure, pore water pressure