Abstract: On October 11, 2018, a large-scale landslide (Baige landslide) took place along the Jinsha River at the junction of Jiangda County in Tibet and Baiyu County in Sichuan Province, which resulted in blockage of the Jinsha River and formed a barrier lake. On November 3, 2018, a second landslide occurred in this area, blocked the river again and raised the water storage capacity of the barrier lake. In order to study the influence of Baige barrier lake on the stability of upstream bank slope during the discharge of the barrier lake through artificial trench, we examined the deformation characteristics and stability variation law of a natural bank slope in the upstream of the barrier lake in the process of water level drawdown using finite element software PLAXIS. Results evinced that: (1) with the discharg of barrier lake, the deformation of slope surface gradually increased, and the maximum displacement at the back edge of the slope reached 8.5 cm, while the deformations in the middle and the front edge were relatively small; (2) in the process of water level descent, the plastic zone at the back edge of the slope expanded downward, yet with no plastic zone penetrated, and meanwhile the safety factor reduced gradually until reaching 1.16; (3) the most unfavorable slipping surface of slope at different stages of water level drawdown remained the same. The exit of the slipping arc located at elevation 3 150 m of the landslide body and about 250 m from the slope foot. Therefore, we conclude that the potential sliding form of the bank slope is a high-level landslide. The research results are of referential value for future prevention and control of landslide disasters in this region.

Key words: Baige landslide, slope stability, barrier lake, PLAXIS, safety factor, plastic zone