*3.1. Mesh and Model*

Figure 3 shows the model of the subgrade with a capillary barrier. The figure on the horizontal axis means the distance from the road's central line. The figure on the vertical axis means the height of the pavement to the bedrock. A subgrade section was selected in Guangzhou. The height of the foundation was 20 m. The height of the subgrade was 6 m. The slope of the shoulder was 1:1.5. Due to the symmetry of the subgrade, the simulation only took half of the subgrade for the research. This paper studied two subgrade models: (1) a conventional subgrade; (2) a subgrade using a capillary barrier. The conventional subgrade was composed of a single soil layer, while the subgrade protected by a capillary barrier added a capillary barrier on the slope shoulder. The subgrade soil was used as fill with a thickness of 0.3 m. The thickness of the gravel was 0.2 m.

**Figure 3.** Mesh of the subgrade with a capillary barrier (unit: m).
