Three Dimensional Seepage Analysis on Diversion Tunnel of Jinping No.2 Hydropower Station

Jinping No.2 Hydropower Station is situated at the large river bend of the main stream of Yalon River in Sichuan Province.It is a diversion type hydropower station with the largest installed capacity on Yalon River.The diversion tunnel is 18-20 km long.It has large diameter and lies in very deep rock stratum.Owing to the very complicated geological conditions of rock stratum and insufficient technical data,back analysis method is used for determining the parameters.As the wide range of study field and the small dimension of the tunnel,the large model combined with small model is applied in the analysis.The analysis uses the continuous medium model.For the large structure face,such as fault,a thin layer water conduction element is used to simulate its conductivity.From the analysis,the maximum leakage of the tunnel during construction is predicted.The impact of tunnel excavation on the surrounding environment is evaluated.