Compacted Gaomiaozi bentonite–sand mixtures are regarded as attractive buffer/backfill materials for nuclear waste deep geological disposal. When the mixture blocks are emplaced, the bentonite dry density as well as the salinity of groundwater is of primary importance for their hydro-mechanical behavior. In this study, the influences of bentonite dry density and water salinity on the swelling pressure and saturated hydraulic conductivity of such mixtures are investigated using the constant volume method. Results indicated that for mixtures having a low sand content, the swelling pressure was only associated with the bentonite dry density, while the hydraulic conductivity was influenced by the presence of sand particles. Exponential relationships were noted among the final swelling pressure, the saturated hydraulic conductivity, and bentonite dry density on the case of distilled water and salt solutions infiltrating. As the salt concentration increased, the swelling pressure and hydraulic conductivity decreased and increased, respectively, and the effects became less significant as the bentonite dry density increased. The higher swelling pressure and lower hydraulic conductivity on specimens infiltrated with calcium chloride solutions were a result of cation exchange reactions and a competition between the swelling potential change caused by the calcium ions in the interlayer of smectite and electrolyte solutions. The present work can provide a reference for the design of dry density of bentonite–sand mixtures as buffer/backfill materials for deep geological disposal.

压实的高庙子膨润土-砂混合物被认为是用于核废料深层地质处置的有吸引力的缓冲/回填材料。当混合块被放置时，膨润土干密度以及地下水的盐度对其水力学行为是最重要的。在本研究中，使用定容法研究了膨润土干密度和水盐度对此类混合物的膨胀压力和饱和导水率的影响。结果表明，对于含砂量低的混合物，膨胀压力仅与膨润土干密度有关，而导水率受砂粒存在的影响。发现最终膨胀压力、饱和导水率、在蒸馏水和盐溶液渗透的情况下，膨润土的干密度。随着盐浓度的增加，膨胀压力和水力传导率分别降低和增加，随着膨润土干密度的增加，影响变得不那么显着。用氯化钙溶液渗透的试样的较高膨胀压力和较低的水力传导率是阳离子交换反应的结果，以及由蒙脱石和电解质溶液夹层中的钙离子引起的膨胀电位变化之间的竞争。该工作可为深部地质处置缓冲/回填材料膨润土-砂混合体干密度的设计提供参考。膨胀压力和导水率分别降低和增加，随着膨润土干密度的增加，影响变得不那么显着。用氯化钙溶液渗透的试样的较高膨胀压力和较低的水力传导率是阳离子交换反应的结果，以及由蒙脱石和电解质溶液夹层中的钙离子引起的膨胀电位变化之间的竞争。该工作可为深部地质处置缓冲/回填材料膨润土-砂混合体干密度的设计提供参考。膨胀压力和导水率分别降低和增加，随着膨润土干密度的增加，影响变得不那么显着。用氯化钙溶液渗透的试样的较高膨胀压力和较低的水力传导率是阳离子交换反应的结果，以及由蒙脱石和电解质溶液夹层中的钙离子引起的膨胀电位变化之间的竞争。该工作可为深部地质处置缓冲/回填材料膨润土-砂混合体干密度的设计提供参考。用氯化钙溶液渗透的试样的较高膨胀压力和较低的水力传导率是阳离子交换反应的结果，以及由蒙脱石和电解质溶液夹层中的钙离子引起的膨胀电位变化之间的竞争。该工作可为深部地质处置缓冲/回填材料膨润土-砂混合体干密度的设计提供参考。用氯化钙溶液渗透的试样的较高膨胀压力和较低的水力传导率是阳离子交换反应的结果，以及由蒙脱石和电解质溶液夹层中的钙离子引起的膨胀电位变化之间的竞争。该工作可为深部地质处置缓冲/回填材料膨润土-砂混合体干密度的设计提供参考。