Freeze–thaw cycles is a seasonal process which occurs in many north regions of soils. Understanding the effects of freeze–thaw cycle on the physico-mechanical behaviours of soils is critical for construction stabilisation and reduce the freeze-thaw damage of foundation engineering. Over the years, studies has been conducted to investigate the effect of freeze-thaw cycles to the periodic strength characteristics of clay. Additive reinforced materials are used to reduce the damages which caused by freeze-thaw cycles and has made series significant contribution to foundation engineering. In this study, bentonite would be added as an additive to investigate the strength characteristics of unsaturated bentonite modified clay after different freeze–thaw cycles. Specimens of natural clay were mixed with different saturation, dry density and bentonite content. The results indicated that dry density, saturation and bentonite content give significant effect on shear strength of bentonite modified clay after freeze–thaw cycles. Meanwhile, the cohesion and internal friction angle of soils gradually attenuated with the increase of dry density, freeze–thaw cycles and saturation. It is found that during the freeze–thaw cycles, the reduction of internal friction angle and cohesion is most obvious at the first freeze-thaw cycle, and gradually stabilized after 7th freeze-thaw cycle. Moreover, results shown that the content of bentonite can effectively improve the cohesion, and maintain positive effects to the internal friction angle. Therefore, appropriate content of bentonite can effectively improve the freeze-thaw resistance of clay.

冻融循环是一个季节性过程，发生在土壤的许多北部地区。了解冻融循环对土壤物理力学行为的影响对于稳定施工和减少基础工程的冻融损害至关重要。多年来，已经进行了研究以研究冻融循环对粘土的周期性强度特性的影响。添加剂增强材料用于减少冻融循环所造成的破坏，并为基础工程系列做出了重大贡献。在这项研究中，将添加膨润土作为添加剂，以研究不同的冻融循环后不饱和膨润土改性粘土的强度特性。混合了不同饱和度的天然粘土样品，干密度和膨润土含量。结果表明，冻融循环后，干密度，饱和度和膨润土含量对膨润土改性粘土的剪切强度有显着影响。同时，土壤的内聚力和内摩擦角随着干密度，冻融循环和饱和度的增加而逐渐减弱。发现在冻融循环中，内摩擦角和内聚力的减小在第一个冻融循环中最明显，并且在第7个冻融循环后逐渐稳定。此外，结果表明，膨润土的含量可以有效地改善内聚力，并保持对内摩擦角的积极作用。因此，适当添加膨润土可以有效地提高粘土的耐冻融性。冻融循环后，饱和度和膨润土含量对膨润土改性粘土的剪切强度有显着影响。同时，土壤的内聚力和内摩擦角随着干密度，冻融循环和饱和度的增加而逐渐减弱。发现在冻融循环中，内摩擦角和内聚力的减小在第一个冻融循环中最明显，并且在第7个冻融循环后逐渐稳定。而且，结果表明，膨润土的含量可以有效地改善内聚力，并且对内摩擦角保持积极作用。因此，适当添加膨润土可以有效地提高粘土的耐冻融性。冻融循环后，饱和度和膨润土含量对膨润土改性粘土的剪切强度有显着影响。同时，土壤的内聚力和内摩擦角随着干密度，冻融循环和饱和度的增加而逐渐减弱。研究发现，在冻融循环中，内摩擦角和内聚力的减小在第一个冻融循环中最明显，而在第7个冻融循环后逐渐稳定。此外，结果表明，膨润土的含量可以有效地改善内聚力，并保持对内摩擦角的积极作用。因此，适当添加膨润土可以有效地提高粘土的耐冻融性。