Novel Approach to Determine Soil–Water Retention Surface

Abstract Models have been developed to represent soils, thereby establishing the unsaturated soil theory. Accurate models include physical deductions based on soil properties. The soil–water retention surface (SWRS) represents the general soil–water retention curve (SWRC), considering the void ratio changes. This study presents a novel model that describes the surface physical behavior. The proposed model demonstrated physical consistency and dependence between the soil hydraulic properties and the void ratio. Additionally, sensitivity analyses were performed to verify the influence of soil parameters on the hydraulic behavior. Literature data of SWRCs at different void ratios were used to generate a 3D surface model by fitting the data points. A continuum SWRS of the specified soil was plotted, soil parameters were calculated, and SWRCs at different void ratios were analyzed. The mathematical relationship between the air-entry value of the soil and its void ratio was also defined. By modeling and validating literature experiments, the proposed model demonstrated the ability to accurately represent hydraulic properties of soils without excessive deformation due to suction increase.