Predictive model for the water retention curve of deformable clayey soils

Tests for determining the water retention curve (WRC) can be time-consuming and tedious, especially with deformable soils for which volume change and water content have to be simultaneously monitored. In some cases, predictive models can become a practical alternative to obtain an estimate of the WRC. However, very few models are available to predict the WRC of deformable materials under increasing suction. In this paper, the modified Kovacs (MK) model, developed initially for incompressible soils, is extended to describe and, in some cases, predict the WRC of deformable clayey soils. This generalization of the MK model is performed by introducing the volumetric shrinkage curve (VSC) in its formulation. A curvilinear equation is proposed to represent the void ratio-suction function e(psi) corresponding to the VSC. This VSC model and the extended MK model (MKd) are validated using experimental data taken from the literature. Empirical relationships are developed for predictive purposes to estimate the parameters involved, using basic geotechnical properties. Applications show a good agreement between measured and calculated WRC.