Experiments are conducted to investigate the effect of a drainage layer in/below saturated tailings on leakage through a hole of various shapes and sizes in a 2-mm-thick HDPE geomembrane. Three cases: no drainage (Case 1), drainage layer between two layers of tailings (Case 2), and drainage layer below tailings and above the GMB (Case 3) are examined. Analytical solutions predicting leakage through a circular GMB hole overlain by tailings with an internal drainage in (Case 2) and below (Case 3) tailings are developed, and match the experimental and numerical results well. Results show that a drainage layer separated from the GMB by a thin layer of tailings (Case 2) gives leakage slightly greater than if no drainage layer is present, but 3-5 orders of magnitude lower than when the drainage is placed directly over the GMB (Case 3). In Case 3, leakage is dependent on the hydraulic conductivity k of both the drainage and subgrade, and is not affected by the tailings. Unlike Cases 1 and 2 where the subgrade has negligible effect on leakage, a low permeability subgrade with k less than 10% of k for the drainage layer is recommended in Case 3 to minimize leakage through geomembrane defects.

进行实验以研究饱和尾矿中/下方的排水层对 2 毫米厚 HDPE 土工膜中各种形状和尺寸的孔渗漏的影响。检查三种情况：无排水（情况1）、两层尾矿之间的排水层（情况2）、尾矿下方和GMB上方的排水层（情况3）。开发了预测通过尾矿覆盖的圆形 GMB 孔渗漏的分析解决方案，其中尾矿（案例 2）和尾矿下方（案例 3）具有内部排水系统，并且与实验和数值结果很好地匹配。结果表明，通过一薄层尾矿将排水层与 GMB 隔开（案例 2），其泄漏量比不存在排水层时稍大，但比排水层直接放置在 GMB 上方时低 3-5 个数量级（案例3）。在案例 3 中，渗漏量取决于排水系统和路基的水力传导率k，并且不受尾矿的影响。与案例 1 和案例 2 中路基对渗漏的影响可以忽略不计，案例 3 中建议排水层采用k小于k的 10% 的低渗透路基，以最大限度地减少土工膜缺陷造成的渗漏。