复杂地基条件下土石围堰施工防渗研究

某水电站上游围堰在围堰左岸基础位于基岩上，右岸基础位于松动体上，中间河床覆盖层自下而上分为三类岩组，其中Ⅰ、Ⅲ类岩组岩层属强透水层，Ⅱ类岩组属中等一强透水层。围堰挡水后将产生集中绕坝渗漏。为解决上游围堰防渗及绕坝渗漏问题，确定最优防渗方案，对上游围堰及基础进行了三维有限元渗流计算。计算结果表明，确定河床覆盖层必须修筑混凝土防渗墙进行防渗，但根据实际的地形条件以及施工难度情况，对右岸松动体的防渗方案做了相应优化，确定采用防渗帷幕进行松动体内的防渗。

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.