Numerical analysis of drying process of soils using finite volume method

The accurate prediction of the moisture content in soil is important for pavement engineering. The MEPDG uses the Enhanced Inte-grated Climate Model (EICM) to consider the effects of environment on the moisture contents of unbound and subgrade soil using models related to unsaturated hydraulic conductivity. These models are mostly empirical and not applicable to relatively dry conditions. This is because at relatively dry condition, the moisture in the pore structure of the soil is not inter-connected. Therefore, the moisture diffusion in porous material controls the moisture migration. When the diffusion coefficient is a nonlinear function of pore relative humidity (RH), there is no closed-form solution of the constitutive differential equation of the moisture diffusion. This study used finite-volume method (FVM) and finite-element method (FEM) for the numerical simulation of the moisture diffusion in soils. The FVM, which is similar to the FEM, uses small and finite-sized elements for simulation, but is based on the law of conservation. Therefore, FVM will be more suitable for flux conservation problems such as moisture diffusion. The FVM results were verified with laboratory experiments and compared with FEM results. The results indicate the applicability of using FVM in the simulation of the moisture migration in soils. © 2018 Chinese Society of Pavement Engineering.