碾压混凝土重力坝的4种防渗结构设计与渗流分析

Seepage analysis of RCC gravity dam with anti-seepage structure of 4 design schemes

采用有限元法(FEM)分析了碾压混凝土(RCC)大坝的应力场和渗流场,上游防渗层采用不同类型的混凝土材料,包括三级配RCC、二级配RCC、常规振捣混凝土(CVC)和富浆振捣RCC。在正常水位和洪水校核水位下,对4种设计方案中防渗层的防渗性能进行了评价。挡水段和泄流段的应力场分析表明,最大拉应力出现在坝踵附近,最大压应力出现在坝趾附近,4种方案的应力分布均满足应力控制标准。渗流场分析表明,方案S3、S4的扬压力水头在防渗区迅速下降,稳定渗流条件下的日渗流计算结果比其他2个方案低约30%~50%,表明CVC和GEVR具有较好的防渗性能。

This study used the finite element method(FEM)to analyze the stress field and seepage field of a roller-compacted concrete(RCC)dam,with an upstream impervious layer constructed with different types of concrete materials,including three-graded RCC,two-graded RCC,conventional vibrated concrete(CVC),and grout-enriched vibrated RCC(GEVR).It also evaluated the anti-seepage performance of the imperious layer in the four design schemes under the normal water level and flood-check level.Stress field analysis of a retaining section and discharge section shows that the maximum tensile stress occurs near the dam heel,the maximum compressive stress occurs near the dam toe,and the stress distributions in the four schemes can satisfy the stress control criteria.Seepage field analysis shows that the uplift pressure heads in schemes S3 and S4 descend rapidly in the anti-seepage region,and that the calculated results of daily seepage flow under the steady seepage condition in these two schemes are about 30%-50%lower than those in the other two schemes,demonstrating that CVC and GEVR show better anti-seepage performance.