考虑土工膜缺陷的石渣坝三维渗流特性分析

Characteristic analysis of 3D seepage field of a geomembrane faced rockfill dam considering defects of geomembrane

以某中型水库覆盖层上土工膜防渗石渣坝为例,重点考虑坝面土工膜缺陷不同的类型、大小及其分布等不利因素,采用有限元法对大坝及地基开展三维渗流场数值模拟,并根据大坝水头分布、渗流量和渗透坡降计算成果,对大坝防渗安全性进行分析评价。结果表明:坝面土工膜缺陷主要影响坝体部分渗流场,局部抬高了浸润线,对坝基及两岸影响小;流经坝体部分的渗流量有大幅提升;缺陷附近膜后垫层发挥了防渗作用,局部渗透坡降增加明显。总体上,该大坝渗控安全能够满足正常运行要求。

Taking a geomembrane faced rockfill dam on thick overburden of a medium-sized reservoir as an example,the finite element method is adopted to carry out the three-dimensional numerical simulation of seepage field of the dam and foundation,focusing on some influence factors,e.g.,different types,sizes and distributions of geomembrane defects.According to the calculation results of dam head distribution,seepage discharge and seepage gradient,the dam seepage safety is analyzed and evaluated.The results show that when the geomembrane has defects,it mainly affects the partial seepage field of the dam body and locally raises the phreatic line,but has little effect on the foundation and abutments.The seepage discharge through the dam body has also been greatly increased.The cushion layer behind the membrane near the defect plays an anti-seepage role,and the corresponding local seepage gradient increases significantly.In general,the seepage prevention design can meet the requirements of normal operation of the dam.