Abstract：After the TGP dam was built，the reservoir will be impounded gradually till the level ascends at least 100 m in about 10 years. As the need of flood prevention，the reservoir water level will fluctuate between 175 m and 145 m. The periodical rise and descent of water level will change the intrinsic water-rock interaction circumstance and condition，which maybe results in the instability of reservoir banks and slopes. Under the fluctuation of different water levels，the seepage-stress fields，the deformation trends and the failure process of landslide are analysed using FLAC4.0. In addition，the change of landslide stability and its influence on bridge foundation after water level fluctuations are discussed in this paper. All these research results will provide technical supports for the stability assess of bridge foundation and the design of project prevention.
