Research on hydro-thermal coupling model of canal foundation soil based on particle grading curve predicting soil-water characteristic curve

Hydro -thermal coupling is the essence of the freeze -thaw process, and theoretical studies of this coupled process have been hot topics in the field of frozen soil. Darcy's law of unsaturated soil water flow, heat conduction theory, and relative saturation and solid -liquid ratio are based on this paper. According to the principle that the cumulative curve of particle gradation of canal foundation soil is similar to soil -water properties. A soil -water characteristic curve is derived using the cumulative particle gradation curve. VG model is then used to fit soil -water characteristic curves to obtain the canal foundation soil's hydraulic characteristic parameters, and the established hydro -thermal coupling model is modified to reflect canal foundation soil hydro -thermal evolution more objectively. A closed system one-way freezing test method is used to verify the feasibility of the proposed method in this part. The results show that the optimal parameters of the VG model of the subsoil are a = 0.06, n = 1.2, and m = 0.17, and the temperature and water fields obtained from the simulation are in good agreement with the measured data, showing the utility of the hydro -thermal coupling model in predicting hydraulic parameters. Analysis of the multi -field interaction mechanism and dynamic coupling process of the canal foundation soil during freezing and thawing. This has great importance for preventing freezing damage in canals and protecting agricultural safety.