Analysis of coupled heat, moisture and air transfer in a deformable unsaturated soil

A new theoretical formulation for the analysis of coupled heat, moisture and air transfer is presented, which is applicable to a deformable unsaturated sail. The approach proposed extends previous analyses of the coupled transport of heat, pore water and pore air to take account of the deformation behaviour of partially saturated soil. A numerical solution of the governing differential equations is achieved by the use of the finite element method as a spatial discretization technique coupled with a finite difference recurrence relationship to describe transient behaviour. Three isothermal test problems are them considered to model the behaviour of unsaturated soil under varying stress and suction conditions. Both heave and collapse due to wetting are simulated. The model is applied to experimental work performed by others for the case of heating of an unsaturated montmorillonite clay and is shown to be capable of producing quantitatively physically correct results. These indicate that strong interactions occur between temperature, pope liquid content, suction and deformation of the soil.