A thermodynamic model for calculating the unfrozen water content of frozen soil

Abstract

On the basis of thermodynamic principles, the relationship between freezing temperature depression and pore radius of soil has been derived. Combined with the soil pore size distribution, this paper proposes a thermodynamic model for calculating unfrozen water content, and investigates the effects of pore radius, nonfreezable layer, and pore shape on unfrozen water content. Comparison of calculated results with the experimental data shows that the model provides a reasonable approximation for calculating the unfrozen water content of frozen soil. Moreover, the mechanism of unfrozen water content change for different soil types, initial water contents can be well explained. The study not only establish a relationship between the unfrozen water content and pore size distributions of soils, but also provide a thermodynamic reference to understand the mechanism of phase transitions in frozen soils.