A theoretical model of the soil freezing characteristic curve for saline soil

• Published in: Journal of hydrology (Amsterdam) 2023-07, Vol.622, p.129639, Article 129639
• Main Authors: Wu, Yandi, Wang, Yijie, Hu, Liming
• Format: Article
• Language: English
• Subjects: Adsorbed water; Capillary water; Frozen saline soils; Ice-salt eutectic; Soil freezing characteristic curve (SFCC); Soil-water characteristic curve (SWCC)
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2023.129639

•A theoretical SFCC model for saline soil is proposed and validated.•The unfrozen water content during two phase transition stages is well predicted.•Eutectic temperature is related to the initial solute concentration and saturation. Soil freezing characteristic curve (SFCC) characterizes the relationship between liquid water content and temperature in frozen soils, which is of significance in simulating the heat, moisture, and solute migration process in the hydrological cycle in cold regions. Soil freezing process of saline soils includes various stages including ice or salt crystallization and ice-salt eutectic. However, most SFCC models ignored the eutectic stage. Based on the framework of chemical potential equilibrium, a theoretical model is developed considering the ice-salt eutectic phenomenon in this study. The model can well predict the change in unfrozen water content in various stages for both low and high initial concentrations from the soil–water characteristic curve (SWCC). The applicability and accuracy of the model are well verified by the published data of the measured phase diagrams of bulk salt solution and SFCCs for different types of soils. The effects of soil type, initial solute concentration, and initial water content on soil freezing process and eutectic temperature are further analyzed using the theoretical model, which is in agreement with reported experimental results. The work provides a comprehensive view to understand the freezing characteristic of saline soils.