土工膜缺陷对土石坝渗流特性的影响及控制措施

由于土工膜因缺陷导致的渗漏问题可能对土工膜防渗土石坝工程安全造成隐患,为此模拟不同的土工膜缺陷大小和位置,分别采用剔除单元法和渗透系数放大法对存在缺陷的土工膜坝面防渗土石坝进行饱和-非饱和三维渗流场有限元数值仿真计算,分析土工膜不同缺陷条件下大坝整体及局部渗流场变化规律。计算结果表明:土工膜缺陷渗漏仅对缺陷附近坝体局部渗流场分布产生较大影响,对大坝其他部位影响不大;土工膜缺陷位置越低,缺陷处水头越大,缺陷渗漏量增加越明显,并使缺陷处膜后坝体浸润线局部抬高。最后,针对土工膜缺陷渗漏提出了若干工程设计控制措施。

Influence of geomembrane defect on seepage property of earth-rock dams and measures of seepage control

Geomembrane defect-induced leakage may cause potential hazards to an earth-rock dam with geomembrane on the dam surface used for seepage control. Therefore, three-dimensional saturated-unsaturated seepage fields with different sizes of geomembrane defects occurring at different locations on the surface of an earth-rock dam were simulated with the finite element method. The laws of variations of the entire and local seepage fields with different geomembrane defects were analyzed. The seepage behavior induced by geomembrane defects was simulated using the methods of removing defect elements and amplifying the permeability, respectively. Results show that defect-induced leakage has significant influence on the local seepage field near the defects and little influence on other parts of the dam body. With the low position of geomembrane defects, the head at defects will increase, leading to significant increases of the total seepage flow and local elevation of phreatic lines across the defects. Finally, some methods were proposed for control of defect-induced leakage in engineering design.