Abstract The hydraulic conductivity of geosynthetic clay liners (GCLs) permeated with deionized water (S0) and NH4+ solutions, with concentrations of 100 mg/L (S100) and 1000 mg/L (S1000), was examined under six dry-wet cycles. The internal properties of virgin, desiccated, and healed GCLs were analyzed and quantified using X-ray computed tomography images. The hydraulic conductivity of the GCLs permeated with S0 and S100 underwent a negligible change during the six dry-wet cycles, whereas that of S1000 increased by almost three orders of magnitude after two desiccations. Each desiccation, after permeating with S0 and S100, generated a completely different macro-crack pattern; however, generation of macro-cracks at the same locations from dry cycles 2 to 6 and an abundance of micro-cracks were typical for S1000. This implies the severe deterioration of bentonite due to multi-desiccations and chemical compatibility with S1000. Moreover, the swell index of bentonite exposed to S1000 was reduced by approximately half, after six dry-wet cycles. Despite the lower volume percentage of macro-cracks for S1000 compared to S0 and S100, the swelling capacity of this bentonite was insufficient to fully heal these cracks. Hence, the swelling properties of bentonite dominate crack volume with regard to determining the hydraulic conductivity of GCLs.

中文翻译：

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铵渗透和干湿循环对土工合成粘土衬垫的导水率和内部特性的综合影响

摘要 用去离子水 (S0) 和 NH4+ 溶液渗透的土工合成粘土衬垫 (GCLs) 的水力传导率在六个干湿循环下进行了检测，浓度分别为 100 mg/L (S100) 和 1000 mg/L (S1000)。使用 X 射线计算机断层扫描图像分析和量化原始、干燥和愈合的 GCL 的内部特性。在六个干湿循环中，渗透了 S0 和 S100 的 GCL 的水力传导率的变化可以忽略不计，而 S1000 的水力传导率在两次干燥后增加了近三个数量级。每次干燥，经过 S0 和 S100 渗透后，产生完全不同的宏观裂纹模式；然而，从干循环 2 到 6 的相同位置产生宏观裂纹和大量的微裂纹是 S1000 的典型特征。这意味着由于多次干燥和与 S1000 的化学相容性，膨润土会严重劣化。此外，经过六次干湿循环后，暴露于 S1000 的膨润土的溶胀指数降低了大约一半。尽管与 S0 和 S100 相比，S1000 的宏观裂纹体积百分比较低，但这种膨润土的膨胀能力不足以完全愈合这些裂纹。因此，膨润土的膨胀特性在决定 GCL 的水力传导率方面支配着裂缝体积。这种膨润土的膨胀能力不足以完全愈合这些裂缝。因此，膨润土的膨胀特性在决定 GCL 的水力传导率方面支配着裂缝体积。这种膨润土的膨胀能力不足以完全愈合这些裂缝。因此，膨润土的膨胀特性在决定 GCL 的水力传导率方面支配着裂缝体积。