Study on the multi-field-coupling model of saline frozen soil considering ice and salt crystallization

Sulfate soil, a typical saline soil in Qinghai Tibet Plateau, has the engineering characteristics of salt expansion and frost heave, which are seriously threatening the operation and safety of engineering buildings. Based on the phase diagram theory, we determined the functions of ice and hydrated salt in pore solution under different concentrations and temperatures. Then we further established a multi-field-coupling model of saline frozen soil considering ice and salt crystallization to simulate the water/salt migration process and the deformation law of saline soil in the cooling process. Compared with the results of unidirectional freezing test, we verified the reliability of the model, indicating that the model well reflected the development of water, temperature, salinity, and deformation of saline soil. Finally, we discussed the variation of each component in sodium sulfate soil, the change process of soil hydraulic conductivity, and the deformation mechanism according to the proposed numerical model. The results provide a theoretical reference for the engineering application of a multi-field-coupling model of saline soil in cold regions.