Field experimental study of the characteristics of heat and water transfer during frost heaving

摘要

During soil frost heave, the hydrothermal effect directly causes many engineering freezing damage problems. To reveal the mechanism of hydrothermal interaction, the dynamic observation of hydrothermal state, frost heave, and freezing depth was conducted in the field for 1 year. Results showed that, the temperature gradient changes rapidly and the freezing rate is slow, moisture can have sufficient time to migrate to the freezing front and produce enhanced frost heave. The reduction of liquid water in unfrozen soil is closely related to the location of the freezing front. The heat flux near the freezing front including the latent heat of in-situ water freezing (largest), the heat flux from the unfrozen soil side (second) and the latent heat of the migrated water freezing (smallest). The latent heat of the moisture migration will be greater than the heat flux from the unfrozen soil side, if the moisture migration occurs. The thermal conductivity of natural ground is not only related to the phase change and moisture content in the soil but also to the frozen soil structure. The results of this study have certain theoretical significance for revealing the heat and fluid flow in seasonal frozen soil area, analyzing the mechanism of freeze-thaw and numerical simulation of hydrothermal coupling.