Abstract: Based on the geological exploration data， the geological model of the open-pit slope in Chengmenshan Copper Mine is established， and the stability of the lakeside open-pit slope is analyzed by considering the different seepage paths and different seepage pressures of lake water. The results show that the seepage of lake water greatly reduces the safety factor of slope. With the increase of lake water level， the scope of slope landslide becomes larger， and the safety factor of slope is lower. The distance between lake shore and open pit has great influence on slope stability. Compared with the safety factor of slope under the same lake water level at different distances， the larger the lake-slope distance D is， the higher the slope safety factor is. Based on the above study results， when the allowable safety factor is 1.2， the minimum safe distance between lake and slope is 60 m under the condition of lake water seepage.

Key words: Lakeside open pit mine, Slope stability, Fluid-solid interaction, Strength reduction method, Safety distance