The impact of time-dependent unsaturated behaviour of virgin and the impact of cation self-diffusion on the time-dependent unsaturated behaviour of exhumed geosynthetic clay liner (GCL) specimens were investigated using a chilled mirror hygrometer. Total suction values (after 7 weeks’ water homogenisation) are reported for ten virgin (six different bentonites) and one GCL exhumed after exposure to the thermo-hydro-mechanical (THM) conditions in Antarctica. The time-dependent unsaturated responses of four different virgin GCLs 1 day and 1 week after hydration are compared with the results at homogenisation and the implications discussed. For the suction (0.1–300 MPa) and water content range (5–140%) examined, the post-water homogenisation water retention behaviour of the GCLs is affected by bentonite characteristics. At a given gravimetric water content, the total suction of GCLs increased with increasing smectite content and total soluble salt content and decreased with increasing total bound cation content in the bentonite. Cation self-diffusion also increased the total suction in the GCL exhumed after exposure to Antarctic THM conditions. It is concluded that the impact of cation self-diffusion on the unsaturated behaviour of a GCL during its time in service before exposure to pollutants needs to be considered in designing hydraulic and gas barriers.

中文翻译：

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南极土工合成粘土衬垫的不饱和行为和阳离子自扩散

使用冷镜湿度计研究了原始土工合成粘土随时间变化的不饱和行为的影响和阳离子自扩散对挖出的土工合成粘土衬垫 (GCL) 样本的随时间变化的不饱和行为的影响。报告了在南极洲暴露于热水机械 (THM) 条件后挖掘出的 10 种原始（六种不同的膨润土）和 1 种 GCL 的总吸力值（经过 7 周的水均质化后）。将水化后 1 天和 1 周四种不同原始 GCL 的时间依赖性不饱和反应与均质化结果和讨论的影响进行比较。对于吸力 (0.1–300 MPa) 和含水量范围 (5–140%) 的检查，GCL 的均质后保水行为受膨润土特性的影响。在给定的重量含水量下，GCLs 的总吸力随着蒙脱石含量和总可溶性盐含量的增加而增加，并随着膨润土中总结合阳离子含量的增加而降低。阳离子自扩散还增加了暴露于南极 THM 条件后挖掘出的 GCL 中的总吸力。得出的结论是，在设计液压和气体屏障时，需要考虑阳离子自扩散对 GCL 在暴露于污染物之前的服务期间的不饱和行为的影响。