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Crystallization is generally considered as the most destructive factor of porous material, but few studies have reported the coupling effects among fluid flow, heat transfer, crystallization and deformation in porous media. In this paper, the driving forces of phase transition were studied initially and then the crystallization kinetics models were established. Moreover, constitutive relations related to saline frozen soil were discussed, and the expression of unfrozen water content in non-equilibrium state was improved. Finally, a thermo-hydro-salt-mechanical coupled model for fully saturated saline frozen soil with phase change was proposed. Validation of the model is illustrated by comparisons between the simulation and experimental results. The predicted values of frost heave, temperature and moisture distribution are consistent with the experimental data, and it is demonstrated that the presented crystallization kinetics approach is valid for studying heat and mass transfer coupled problem with phase change in porous media. [ABSTRACT FROM AUTHOR]

Abstract: Snow cover is a common and relatively stable land cover condition in winter for cold north regions in China. Snow cover has significant effects on water and heat transfers in frozen soil; it needs to be considered in the study of frozen soil water–heat coupled movements. On the basis of previous research results and physical process analysis of water and heat movements in snow cover and soil, a snow cover–soil union water–heat coupled movements model is established in this paper. The numerical simulation was conducted by using a finite difference method. The results indicate that the simulated values have a similar trend to the measured values and the numerical simulation had big relative errors. However, the average absolute errors of the total and liquid moisture content in frozen soil were all less than 4%, and that of the frozen soil temperature was 1.37 °C. The errors of the numerical simulation were still within the acceptable range. Thus, the snow cover–soil union water–heat coupled movement model constructed in this paper is rational. [Copyright &y& Elsevier]