A NEW EQUATION FOR THE SUCTION INDUCED SHRINKAGE OF CLAYEY SOILS

An increase of the suction applied to a deformable soil may induce shrinkage and desaturation. This makes the determination of the water retention curve (WRC) of such soils more complex, as one needs to follow simultaneously the volumetric shrinkage curve (VSC) and the water content. Descriptive and predictive models can be useful to assess the behaviour of compressible soils. After reviewing typical results obtained on relatively soft and initially saturated clayey soils, the authors introduce new equations to describe the VSC. A simplified tree linear segment representation, inspired by the consolidation theory, is first used. It is then generalised using a curvilinear equation. The proposed models describe the VSC in terms of the change of void ratio e with an increase in suction ψ. Experimental data are used to validate the descriptive capabilities of the VSC models. For predictive purposes, empirical relationships are proposed to estimate the model parameters from the liquid and plastic limits, solid grain density, and initial void ratio. The typical results shown here indicate a good agreement between measured and calculated VSC. RÉSUMÉ Une augmentation de la succion appliquée à un sol déformable induit un retrait et une désaturation. La détermination de la courbe de rétention d'eau (CRE) de tels sols devient complexe car il faut en même temps connaître la courb