Evaluation of frost heave in clay soils

Abstract

Frost heaving in clayey soils with a low coefficient of permeability raises a lot of questions regarding the cryosuction, surface tension forces, and accompanying phase transfer of water. The freeze-thaw laboratory test results were considered in this work in terms of temperature and volumetric parameters change, dry density, and water mass transfer. The article presents a model for calculating the mass transfer of water (vapour) in the gas state under the influence of cryogenic forces. Findings include the improved understanding of the heat and mass transfer phenomenon during the unidirectional freezing of soils in an open system. Most of the tests for engineering properties registered a slight reduction in relation to strength, cohesion, and angle of internal friction. However, there was a significant increase in the coefficient of permeability after the freeze-thaw cycles with initially dense compacted soil samples, which was due to loosening and moistening of the soil samples during the heave at sub-zero temperatures. The conceptual model for frost heave in soils was developed based on the vapour mass transfer. There was presented algorithm of vapour flow calculation in unsaturated soils using fundamental thermodynamic equations.