The volumetric behavior of clayey soil-rock mixtures under freeze-thaw action is very important for the design of anti-frost heave in cold-region engineering. However, existing studies mainly focus on the effect of freeze-thaw cycles on the global volume change of fine-grained soils, and few attempts have focused on mixed soils with coarse particles such as clayey soil-rock mixtures. In this study, a series of laboratory freezing-thawing tests were conducted to investigate the effects of the freeze-thaw cycles and rock content on the global volume change, diameter change, and height change behaviors of cylindrical soil-rock mixture samples. The results demonstrate that: 1) the volumetric behavior of the samples under freeze-thaw cycles is closely related to the rock content, which is mainly because different rock contents dominate the different skeleton structures. 2) For samples with 0%, 10%, and 30% rock content, the global volume of compacted samples shows shrinkage upon freezing and expansion after thawing. However, the global volume of the sample with 50% rock content began to shrink after three freeze-thaw cycles. 3) Compared with the samples not subjected to freeze-thaw weathering, the height of samples with 0%, 10%, and 30% rock content shows shrinkage upon freezing and expansion after thawing no matter what the number of freeze-thaw cycles is. However, the diameter and height of the sample are always shrinking, regardless of whether they are frozen or thawed. 4) Upon freezing, the shrinkage of the sample's global volume and diameter tends to decrease linearly with the increase of rock content, but the shrinkage of the sample's height is not sensitive to the change of rock content. Upon thawing, the global volume and height of the sample exhibit a trend from expansion to contraction with increasing rock content, but the shrinkage of the diameter of the sample is nearly the same no matter what the rock content is. Furthermore, a computed tomography (CT)-based mesoscopic structural characteristic and two idealized schematic diagrams well illustrated the evolution mechanism of the volumetric behavior of an unsaturated clayey soil-rock mixture subjected to freeze-thaw cycles.

冻融作用下黏性土石混合体的体积行为对寒区工程抗冻胀设计具有重要意义。然而，现有的研究主要集中在冻融循环对细粒土全球体积变化的影响，很少有尝试集中在具有粗颗粒的混合土壤，如粘土-岩石混合物。本研究通过一系列实验室冻融试验研究冻融循环和岩石含量对圆柱形土石混合物样品的整体体积变化、直径变化和高度变化行为的影响。结果表明：1）冻融循环下样品的体积行为与岩石含量密切相关，这主要是因为不同的岩石含量支配着不同的骨架结构。2) 对于岩石含量为 0%、10% 和 30% 的样品，压实样品的整体体积表现为冻缩和解冻后膨胀。然而，岩石含量为 50% 的样品的全球体积在三个冻融循环后开始缩小。3) 与未进行冻融风化的样品相比，0%、10%和30%岩石含量的样品无论冻融循环次数多少，在冻融后的高度均出现冻胀现象。然而，无论是冷冻还是解冻，样品的直径和高度总是在缩小。4）冷冻后，样品的整体体积和直径的收缩率随着岩石含量的增加呈线性减小的趋势，但样品高度的收缩对岩石含量的变化不敏感。解冻后，样品的整体体积和高度随着岩石含量的增加呈现由膨胀到收缩的趋势，但无论岩石含量如何，样品直径的收缩几乎相同。此外，基于计算机断层扫描（CT）的细观结构特征和两个理想化的示意图很好地说明了经受冻融循环的非饱和粘土-岩石混合物的体积行为的演变机制。但无论岩石含量如何，样品直径的收缩率几乎相同。此外，基于计算机断层扫描（CT）的细观结构特征和两个理想化的示意图很好地说明了经受冻融循环的非饱和粘土-岩石混合物的体积行为的演变机制。但无论岩石含量如何，样品直径的收缩率几乎相同。此外，基于计算机断层扫描（CT）的细观结构特征和两个理想化的示意图很好地说明了经受冻融循环的非饱和粘土-岩石混合物的体积行为的演变机制。