季节冻土区含砂低液限黏土冻融过程试验研究

为研究季节冻土区含砂低液限黏土在不同埋深地下水补给时的单向冻融过程,采用由箱体、制冷/热系统和地下水补给系统等构成的冻融系统装置,对大尺寸土体模型进行单向冻融试验。试验结果表明:在冻融过程中,各土层平面的温度、含水率与冻融量均分布不均匀,且三者之间相互影响;在地下水补给下,土体的冻胀量大于融沉量,且融沉时长小于冻胀时长;不同埋深地下水对冻融的影响主要表现在对土体冻前初始含水率的影响,进而影响温度梯度和冻结锋面的变化,进一步影响未冻水的迁移、冻胀量和融沉量等发展,因此,冻融作用为温度场、水分场和位移场等复杂的多场耦合作用的结果。

Experimental study on freeze-thaw process of sandy clay with low liquid limit in seasonal frozen soil region

In order to study the unidirectional freeze-thaw process of sandy clay with low liquid limit under groundwater recharge of different depths, the unidirectional freeze-thaw tests on large scale soil mass model were carried out using the freeze-thaw system device consisting of the box, cooling / heating system, groundwater recharge system, etc. The results showed that the temperature, moisture content and freeze-thaw volume of each soil layer plane were not evenly distributed in the freeze-thaw process and counteracted with each other. With groundwater recharge, the amount of frost heaving of the soil was greater than that of the thaw subsidence, and the duration of the latter was shorter than that of the former. The effects of different groundwater depths on the freezing and thawing mainly manifested in their influence on the initial water content before freezing, which in turn affected the temperature gradient and the change of frozen front, and further affected the development of unfrozen water migration, frost heaving volume and thaw subsidence volume. Therefore, the freeze-thaw effect is the result of complex multi-field coupling of temperature field, water field and displacement field.