Freezing and thawing of soil have a significant impact on the thermal‐hydrological processes in cold regions. Freezing point and unfrozen water content are key variables characterizing the freezing and thawing of soil. The testing results show that unfrozen water content is independent of initial water content in nonsaline silt, based on which a unified model for a soil freezing characteristic curve (SFCC) is presented. The SFCC describes the relationship between unfrozen water content and temperature for variably‐saturated saline soils. It is also demonstrated that the SFCC can describe the variation of soil freezing point with respect to water content and salt concentration. The SFCC model is validated by comparing the experimental data to the calculated result for unfrozen water content and freezing point in a variety of conditions. When the initial water content varies in saline soil, the SFCC changes with constant initial salt concentration, but it remains unchanged with constant gravimetric salt content. The SFCC model can be adopted in the simulation of thermal‐hydrological processes in arid and saline lands and coastal regions. Finally, an example of thermal‐hydrological processes was simulated with the new SFCC model to show the application of the presented model.

中文翻译：

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饱和饱和盐渍土的统一土壤冻结特性

土壤的冻结和解冻对寒冷地区的热水文过程有重大影响。冻结点和未冻结的水分含量是表征土壤冻结和解冻的关键变量。试验结果表明，非盐分淤泥中的未冻结含水量与初始含水量无关，在此基础上建立了土壤冻结特征曲线的统一模型。SFCC描述了可变饱和盐渍土壤的未冻结水分含量与温度之间的关系。还证明了SFCC可以描述土壤冰点相对于水含量和盐浓度的变化。通过将实验数据与各种条件下未冻结水含量和凝固点的计算结果进行比较来验证SFCC模型。当盐渍土中的初始水分含量变化时，SFCC随初始盐浓度的变化而变化，而对于恒定重量盐含量则保持不变。SFCC模型可用于干旱，盐碱地和沿海地区的热水文过程模拟。最后，用新的SFCC模型模拟了一个热水文过程的例子，以说明所提出模型的应用。