Research on Construction Anti-seepage of Earth-rock Cofferdam of Complex Foundation

The left bank foundation of one hydropower station upstream is on bedrock,the right bank foundation is on the loosening body.The upstream overburn layer is devided into three kinds of rocks.The I and III rock layer are the strong leakage layers,and the II layer is medium leakage layer.Central dam circle leakage will appear after retaining the water of cofferdam.To calculate the three-dimensional finite element of the upstream cofferdam and foundation in order to solve the problems of anti-seepage and dam circle leakage of upstream cofferdam and choose the optimum plan.The calculation shows that we must build the concrete anti-seepage wall of the river body overburn layer.According to the real terrain condition and the difficulty of construction,we optimize the anti-seepage plan to the loosening body of the right river bank and decide to choose the anti-seepage curtain to prevent the seepage of the loosening body.