The Jinping II hydropower plant is made up of low sluice gate

long tunnel and powerhouse arranged at the end of the power tunnel

and the geological conditions at the powerhouse is quite complicated. II

III and IV surrounding rocks coexist in the area of powerhouse at the end of power tunnel. Considering the complicated engineering geological environment

engineering geological condition

hydraulic condition

stability of surrounding rock project

investment and so on are analyzed; the advantages of choosing powerhouse longitudinal axis of N35°E and the reasonabilities of canceling tailrace surge chamber and using two-cavern scheme are discussed. Constructing practice proves that the layout scheme not only can meet the criterion of cavern stability and operation safety of generating units

but also can save engineering cost and shorten the construction time.