九甸峡混凝土面板堆石坝河床防渗结构研究

Study on impervious structure of riverbed for concrete faced rock-fill dam of Jiudianxia Water Control Project

九甸峡水利枢纽工程混凝土面板堆石坝坝址河谷狭窄,岸坡陡峻,河床分布深厚覆盖层。根据地形地质条件,采用了大坝直接修建在覆盖层上的方案,其河床防渗的结构形式是整个大坝防渗系统的关键。设计考虑了单防渗墙柔性连接、双防渗墙柔性连接、双防渗墙刚性连接等3个方案,采用三维非线性有限元方法,对各个方案坝体和面板的位移反应、应力反应,以及周边缝和面板接缝的位移反应等进行了计算分析。研究了不同方案的特点和规律,确定了合理的设计方案,经实施验证,效果良好。

The concrete faced rock-fill dam of Jiudianxia Water Control Project is located at a narrow valley with steep slopes on both the banks and deep overburden upon the riverbed. In accordance with the geological and topographic conditions therein, a scheme of building the dam directly on the overburden is adopted, and then the pattern of the impervious structure for the riverbed becomes the key-link of the whole anti-seepage system of the dam. Therefore, three schemes, i.e. single cut-off wall with flexi- ble joint, double cut-off wall with flexible joint and rigid cut-off wall are considered during the design concerned; for which the displacement response and stress response of both the dam body and the face slab as well as the displacement responses at the pe- ripheral joint and the joint of the dam slab axe calculated and analyzed with 3D nonlinear finite element method for all the schemes. The characteristics and laws of each scheme axe studied, and then a reasonable design scheme is consequently decided. At last, a better impervious effect is demonstrated through the practical verification.