添加沸石对黏性土-膨润土竖向隔离墙材料压缩和渗透特性的影响

土-膨润土系竖向隔离墙广泛应用于工业污染场地和地下水修复工程。通过坍落度和一维压缩固结试验研究添加沸石对黏性土-膨润土竖向隔离墙材料的工作性，以及压缩和渗透特性。黏性土选用高岭土，沸石-高岭土-膨润土试样中沸石掺量为2%～40%。试验结果与以往沸石-砂-膨润土竖向隔离墙材料以及击实沸石-膨润土混合土研究结果进行对比，明确沸石掺量和粒径对压缩和渗透特性的作用规律。试验结果显示，满足隔离墙材料施工要求的含水率范围随沸石掺量增加而增大，并处于液限的0.96～1.18倍。添加细颗粒沸石对试样的压缩指数和渗透系数影响较小，渗透系数小于10-9 m/s。相反，添加粗颗粒沸石将导致微孔隙尺寸增大，并形成水能够通过的沸石网架结构，将显著增大渗透系数。试样渗透系数能够通过考虑孔隙比和液限的经验公式进行良好的预测。

Effects of addition of zeolite on compressibility and hydraulic conductivity of clayey soil-bentonite backfills for slurry-trench walls

A comprehensive laboratory investigation on the workability, compressibility and hydraulic conductivity of fine-grained zeolite-amended clayey soil-bentonite backfills is conducted via a series of slump and oedometer compression tests. Kaolin is used as the control clayey soil, and it is amended with various contents of bentonite and zeolite to prepare zeolite-amended kaolin-bentonite (ZKB) backfills. The study results are compared with those of zeolite-amended sandy soil/Na-bentonite backfills as well as compacted zeolite-bentonite liners reported in previous studies to clarify the effects of zeolite content and zeolite grain-size on the compressibility and hydraulic conductivity. The results indicate that the water content required to achieve a target slump (100-150 mm) increases with increasing zeolite content, and is approximately in the range of 0.96 to 1.18 times the liquid limit. The results reveal that the hydraulic conductivity of the zeolite-amended clayey soil-bentonite backfills is generally lower than the typical regulatory limit (10-9 m/s). The addition of fine-grained zeolite has little influence on the compressibility and hydraulic conductivity of clayey soil-bentonite and sandy soil/Na-bentonite backfills. In contrast, the addition of coarse-grained zeolite is likely to considerably increase the hydraulic conductivity of soil-bentonite backfill. Finally, a proposed empirical method is examined for predicting the hydraulic conductivity of the backfills in this study. The predicted hydraulic conductivity values are found to fall in the range of 1/3 to 3 times those obtained from the oedometer tests.