**3. Calculation Model of the Subgrade with a Capillary Barrier**

It is difficult to study wetting deformation using an analytical solution. For one thing, the soil water characteristic curve and the permeability coefficient equation of soils are both nonlinear. For another, the strength constitutive relationships of soils are complicated. To quantitatively analyze the deformation and stability of the subgrade protected by a capillary barrier during the rainfall, Geo-Studio 2018 R2 software (version 9.1.1.16749) was used to carry out a numerical simulation study in this paper. Geo-Studio is an overall analysis tool for a set of geological structure model software. The test sections in this paper included SLOPE/W (slope stability analysis module), SEEP/W (groundwater seepage analysis module), and SIGMA/W (rock and soil stress and deformation analysis module).
