Geosynthetic clay liners (GCL) are increasingly being used as a major component of barrier systems replacing compacted clay liners due to their very low permeability and speed of installation. Researchers and practitioners have identified the critical role of the GCL overlap that presents constant challenges encountered in maintaining the designed hydraulic conductivity. This study presents a series of flow box tests conducted to evaluate and improve understanding of the combined effect of each of the four contributing factors, namely, overlap width, supplemental bentonite applied at the overlap, the overburden confining stress, and the hydraulic head acting on the GCL overlap. The findings reveal that the overlap width is the most significant parameter affecting the design hydraulic conductivity. The application of a minimum overburden stress to maintain the designed hydraulic performance is also recognised as important. The effect of confinement due to higher hydraulic heads is of interest to practitioners. The supplemental bentonite has the least effect on the GCL overlap hydraulic performance even though it enhances the function of the overlap seam. This knowledge addresses the inadequacy of published GCL overlap experimental data comparing the effect of different factors affecting its hydraulic performance. It also assists industry practitioners to design and specify the overlap criterion for a specific application depending on the product specifications and site conditions. The results of this research will help minimise failures of liner systems in barrier applications such as landfills, mines, tailing dams substantially to reduce the potential risk of groundwater contamination.

土工合成的粘土衬里（GCL）由于其极低的渗透性和安装速度而越来越多地用作代替压实粘土衬里的屏障系统的主要组成部分。研究人员和从业人员已经确定了GCL重叠的关键作用，这在保持设计的水力传导性方面提出了不断的挑战。这项研究提出了一系列的流箱测试，以评估和增进对四个影响因素中的每一个的综合作用的理解，这四个因素分别是重叠宽度，在重叠处施加的补充膨润土，上覆限制压力以及作用在上面的液压头GCL重叠。研究结果表明，重叠宽度是影响设计水力传导率的最重要参数。人们还认为，施加最小的上覆应力来维持设计的水力性能也很重要。由于液压头较高，限制作用引起了从业者的兴趣。补充膨润土即使增强了搭接缝的功能，对GCL搭接水力性能的影响也最小。该知识解决了已发布的GCL重叠实验数据不足的问题，该数据比较了影响其水力性能的不同因素的影响。它还可以帮助行业从业者根据产品规格和现场条件设计和指定特定应用的重叠标准。这项研究的结果将有助于最大程度地减少在垃圾填埋场，矿山，