Estimation of the soil-water characteristic curve from the grain size distribution of coarse-grained soils

Coarse-grained soil, such as aggregate and coarse sand, is commonly selected to construct a capillary barrier system (CBS). The barrier effect in the CBS is mainly dependent on the hydraulic properties of the coarse-grained soils. It is noted that direct methods (such as experimental measurement) for the determination of the hydraulic properties (including the soil-water characteristic curve (SWCC) and coefficient of permeability) of soil are time-consuming and costly. As a result, indirect methods for the determination of the SWCC and permeability function of soil are commonly adopted by researchers and engineers. In this paper, a new method is proposed for the estimation of the SWCC from the grain-size distribution (GSD) of coarse-grained soils. The proposed method is based on the assumptions that the soil does not experience any volume change and the hysteresis of the SWCC is ignored. A contact angle larger than zero is adopted in this study. The results computed from the proposed model agree well with the experimental data from published studies.