Bimodal Soil&#x2013;Water Retention Curve and <i>k</i>-Function Model Using Linear Superposition

Abstract

Progress in the study of unsaturated soils and their application in practical geotechnics could be partially attributed to the advancement of their modeling and computational technologies. The soil–water retention curve (SWRC) and k-function are fundamental hydraulic properties of unsaturated soil that are important in the analysis of soil states. This study presents a new model to represent the hydraulic properties (SWRC and k-function) of bimodal soils using linear curve superposition. The resulting SWRC model was validated for common bimodal soils, and the k-function was then obtained. The relationship between the model and soil porosimetry was also deduced, leading to a better understanding of the physical influence of the model's parameters. In addition, based on the model, a solution was proposed to simulate the soil infiltration process involving partial differential equations and numerical methods. The model's efficiency in representing bimodal soils was proven, and the results from subsequent analyses confirmed its physical consistency. Therefore, the proposed model could address problems in real-world geotechnical practices.