Compared with the ordinary landslide

factors affecting the stability of the reservoir bank ancient landslide are much more. In addition to the regular factors

the stability is influenced by the water level change obviously. Moreover

the reservoir bank ancient landslide would become geological hazard easily

which causes great danger to human life and property. On the basis of an ancient landslide project of a reservoir

mechanical properties of sliding zone are investigated by the in-situ shear test

laboratory shear test and standard penetration test; and the regularity of influence of water level change on the ancient landslide stability is analyzed. The U-shaped changing regularity of safety factor of Egongdai landslide with water level is obtained. Methods presented in reference [12] are that landslide type can be identified by stress field

and then in high stress level sites reinforcement can be used to reduce stress level to increase safety factor. By the above methods

the upper region of Egongdai ancient landslide has thrust load-caused features; while the bottom region has retrogressive features. Therefore

the Egongdai landslide can be defined as combined landslide; and the upper and bottom regions should be reinforced. The influence on stress field of landslide by different reinforcement schemes are compared; and relationship between stress and displacement fields of the landslide and factor of safety of anti-sliding pile is studied. Results show that the optimal reinforcement site is the one of higher stress level and displacement. As for Egongdai landslide

the bottom region is also with high stress level. Considering the construction conditions and economy

an earth berm was finally constructed at the toe of Egongdai landslide 3 years ago. It is proved that determination of reinforcement site by stress level is reasonable. Research results can provide good reference to other similar projects.