This paper investigated the freezing processes of Qinghai-Tibet silty clay within an added quartz sand layer (QSL) under different one-dimensional freezing temperature gradients by using computed tomography scanning and image acquisition technologies in an open system. The heat transfer, cryostructure formation and water migration processes and mechanisms were discussed. The results reveal that the temperature of the samples was essentially steady within 12 h, and the addition of the QSL has a significant impact on the temperature distribution in the samples. The moisture content of the QSL and the frozen part of the sample increased, while the moisture content of the unfrozen zone decreased significantly after being frozen for 120 h. The QSL was able to effectively limit liquid water migration, however, there was still vapor migration in the samples. Ladder-like and net-like cryostructures formed in the vertical sections of the sample while polygon cracks formed in the horizontal sections, which providing pathways for moisture migration. The saturated vapor pressure difference which calculated by the Antony Equation can be used as the driving force for vapor migration from the unfrozen zone to the frozen zone. From both an experimental and theoretical standpoint, this work is intended to aid research into the physical process and mechanism of sand interbedded stratum and foundation freezing.

采用计算机断层扫描和图像采集技术，在开放系统中研究了不同一维冻结温度梯度下青藏粉质粘土在添加石英砂层（QSL）中的冻结过程。讨论了传热、低温结构形成和水迁移过程和机理。结果表明，12 h内样品温度基本稳定，QSL的加入对样品温度分布有显着影响。QSL和样品冷冻部分的水分含量增加，而未冷冻区的水分含量在冷冻120 h后显着降低。QSL 能够有效地限制液态水的迁移，然而，样品中仍有蒸气迁移。阶梯状和在样品的垂直部分形成网状低温结构，而在水平部分形成多边形裂缝，为水分迁移提供了途径。用安东尼方程计算的饱和蒸汽压差可以作为蒸汽从未冻区向冻区迁移的驱动力。从实验和理论的角度来看，这项工作旨在帮助研究砂互层地层和地基冻结的物理过程和机制。