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土体在冻融过程中的水热特征对于冻胀及工程稳定性具有决定性作用。以青藏粉质黏土为例,采用时域反射法(TDR),测量并分析了不同初始含水率条件下的土样在冻融过程中的水热变化特征,对比了冻融过程中的水热变化及其差异性,采用Anderson等、徐敩祖等和Michalowski提出的以温度为变量的未冻水计算公式,分别计算了不同初始含水率土样在不同温度条件下的未冻水含量。结果表明:冻融过程的土样水分和土样中心温度随时间的变化均可分为三个比较明显的变化阶段,冻结过程和融化过程的变化特征略有不同,除了环境影响和探头自身因素外,我们将其归因于冻融过程的未冻水“滞后效应”。在快速冻融过程中,未冻水含量随温度的变化则表现出渐变的特征。通过对比三种典型未冻水含量的计算方法发现,通过拟合得到的方程计算结果的正确性较高。
The hydrothermal characteristics of soil during freeze-thaw process have a decisive effect on frost heaving and engineering stability. Taking the Qinghai-Tibetan silty clay as an example, the time-domain reflectometry (TDR) was used to measure and analyze the hydrothermal characteristics of soil samples under different initial moisture content in the freeze-thaw process. The water-heat Changes and their differences, using the non-freezing water temperature variation formula proposed by Anderson et al., Xu Tzu-zu et al. And Michalowski, the unfrozen water contents of soil samples with different initial water contents at different temperatures were calculated respectively. The results show that the changes of soil moisture and soil sample center temperature with time can be divided into three distinct phases: the change of the freezing process and the melting process are slightly different, except for the influence of the environment and the probe itself In addition, we attribute this to the unfrozen water “lag effect ” of the freeze-thaw process. In the rapid freeze-thaw process, unfrozen water content showed a gradual change with temperature. Comparing the calculation results of three kinds of typical unfrozen water, it is found that the correctness of the calculation result obtained through the fitting is high.