A unified model of capillary-film water migration in frozen soil and its experimental verification

In view of the fact that it is difficult to apply the capillary water migration mechanism to explaining the formation of frozen fringes and discontinuous segregation ice, and it is also difficult to apply the film water migration mechanism to explaining the uneven frost heave caused by water migration between pores and cracks, based on the capillary theory and the frozen fringe theory, a unified model of capillary-film moisture migration in frozen soil was established by adding a group of capillaries with different pore diameters to the frozen fringe and adding an unfrozen water film to all capillary walls.With this model, the distributions of liquid pressure, ice pressure, and driving force in the frozen large pores and unfrozen small pores were analyzed from the perspective of hydraulic driving, and the hydraulic driving force and the surface adsorption force at the warm side of the ice lens were unified.By referring to the formation mechanism of segregation ice, the governing equation of segregation-freezing temperature was derived.Furthermore, according to the variation laws of surface adsorption force and frozen fringe permeability coefficient with segregation freezing temperature, the explicit equation of moisture migration velocity is provided on the basis of the Darcy's law.Finally, the main parameters used in the frost heave test of Konrad (1980) were substituted into the explicit equation, and it was found that the theoretical calculation results were highly consistent with the experimental results, validating the correctness of the unified model. © 2022, Editorial Office of China Civil Engineering Journal. All right reserved.