小浪底水库坝基防渗墙裂缝对渗流控制的影响

Effects of Crack of Cutoff Wall at the Xiaolangdi Reservoir Dam Foundation on Seepage Control

小浪底水库坝址处河床覆盖层最深达70余米,采用混凝土防渗墙控制强透水地基的渗流。按三维渗流计算结果表明:防渗墙出现裂缝的位置越高,防渗墙下游心墙底部的相对水头越大,裂缝靠心墙底部最危险,因此,确保心墙与防渗墙连接处的施工质量至关重要;防渗墙出现裂缝开度小于0.3cm时,对渗流场的影响不大,防渗墙下游心墙底部最大相对水头值仅为2.02％;防渗墙完好,上游天然淤积铺盖没有明显防渗作用,只有当防渗墙出现裂缝或开叉时,淤积铺盖的防渗作用才比较明显。

Overburden on river bed at the dam site of Xiaolangdi Reservoir reaches up to more than 70m.Con-crete cutoff wall was used to control the seepage of strong permeable dam foundation.Result of three di-mensional seepage calculation showed that the higher the crack on the cutoff wall is,the higher the relativewater head at the bottom of the lower core wall is,and crack at the bottom of the core wall is the most dan-gerous.Hence it is of utmost importance to assure fine construction quality in the connection of core wall tocutoff wall.The effect on seepage is small when the opening of cutoff wall crack is less than 0.3cm,themaximum relative water head at the bottom of lower core wall is only 2.02%.The upper natural desiltedblanket has no obvious effect of anti-seepage when the cutoff wall is well constructed.Only when there iscrack on the cutoff wall is the effect of Blanket obvious.