Study on the coupled heat-water-vapor-mechanics process of unsaturated soils

Abstract

Freezing of unsaturated soils jointly involves heat transfer, water-vapor migration, water-ice and water-vapor phase changes and deformation. To understand this freezing, we conducted a series of one-dimensional freezing tests to study the influences of the initial water content and cooling temperature on the water-vapor migration and deformation of unsaturated soils. Results show that the initial water content determines the water and vapor migration intensity and deformation of unsaturated soils. Vapor migrates prominently and frost heave develops slowly when the initial water content is lower than a critical value. Above this value, the liquid water migration dominates, and frost heave develops rapidly. It is also found that the cooling temperature dominates water and vapor fluxes in such a manner that a higher cooling temperature leads to faster migrations of water and vapor in unsaturated soil. We further analyzed the coupled heat-water-vapor-mechanics process of unsaturated soils and proposed a coupled heat-water-vapor-mechanics model. The simulated temperatures, volumetric water content, and displacement agree well with those measured data, validating that the model can describe effectively the coupled heat-water-vapor-mechanics process in freezing unsaturated soils.