Equations for modeling the shrinkage behavior of unsaturated soils

The relationship between the soil volume and water content (i.e., either gravimetric or volumetric) is referred to as the soil shrinkage curve (SSC). Several researchers have proposed models for predicting the SSCs for fine-grained soils in the literature. However, a valid theoretical framework that can be reliably extended for modeling shrinkage curves is still lacking. In this study, a framework is proposed for modeling the SSCs by extending the assumption that the soil volume change under matric suction is strongly related to variation of pore size distribution. The assumption for modeling SSCs is consistent with the well-established method for modeling the soil water characteristics curves. The equations based on the proposed framework were found to be valuable in the reliable prediction of the shrinkage curves of various soils. The relationships between the proposed SSC equations and the widely used models from the literature are also discussed. The present study provides a new approach for modeling the SSCs that can be used for interpreting and modeling the complex hydro-mechanical behaviors of unsaturated soils.