Saline soils in cold regions present complex engineering challenges due to the strong interactions among temperature, moisture, stress, and salt migration. To elucidate these coupled mechanisms, this study established a comprehensive thermo–hydro–mechanical–salt (THMS) four-field coupled mathematical model for sulfate saline soils subjected to unidirectional freezing. The model integrates water flow, heat transfer, salt transport, and mechanical deformation, explicitly considering the phase transitions of water and sodium sulfate crystallization. Laboratory freezing tests using soils from Korla, Xinjiang, China, were conducted to quantify moisture–salt migration and salt heave deformation, and the results were employed to validate the proposed model via numerical simulations in COMSOL Multiphysics (version 6.2). The results indicate that both water and salts migrate toward the cold end, where mirabilite (Na2SO4·10H2O) crystallization induces localized volumetric expansion and measurable heave deformation. The predicted salt heave deformation (3.47 mm, 3.47%) agrees well with the experimental results, confirming the model’s reliability. This integrated THMS framework provides a robust theoretical and numerical basis for analyzing multifield interactions in sulfate saline soils and supports engineering design in cold-region saline environments.
Han et al. (Mon,) studied this question.