Abstract: The surrounding rock stability and structural load bearing features of surge tank in construction period are key technical issues in the design. The surge tank of Lizhou hydropower station in different construction schemes is taken as an example to research the excavation supporting effect, stress deformation law, surrounding rock stability, lining structure stress distribution and reinforcement. The research is carried out through 3-D nonlinear finite element method. The stress deformation and plastic zone distribution and stability of the lining surrounding rock, and slope stress in different schemes are revealed. Construction scheme and optimization measures are recommended. The research result provides reference for the optimization design of the project. 

Key words: surge tank, 3-D finite element, stress deformation, surrounding rock stability