Soil-Water Characteristic Curve Model Based on Particle Size Distribution and Pellicular Water

Traditional models for predicting soil-water characteristic curve (SWCC) based on particle size distribution curve require segmentation of the curve when calculating water content and often neglect the pellicular water (also known as film water) content on the surface of soil particles. This significantly limits the prediction accuracy. To address these issues, this study assumes point-to-point contact between particles, employs the Weibull function to characterize the particle size distribution curve, determines the capillary water content using the Young - Laplace equation, and accounts for the influence of film water content. On this basis, a new SWCC model considering particle size distribution and film water is developed. Twenty-six soil samples from the Unsaturated Soil Database (UNSODA) are selected for validation and comparison with the AP and MV models. The results indicate that the proposed model based on particle size distribution and film water can predict the SWCC more accurately and significantly reduces the prediction error of water content in the high-matrix-suction section.