Modelling unsaturated soil behaviour in stress-saturation space

This paper presents an alternative approach for interpreting unsaturated soil behaviour. In this approach, all constitutive laws are built in the space of stress versus degree of saturation. A new volume change equation is proposed in terms of stress and degree of saturation, to give a better explanation to the non-linear change of soil compressibility under constant suctions. The soil compression index is assumed to be a function of the effective degree of saturation. The yield surface is established in the plane of the effective degree of saturation and the Bishop effective stress. The proposed model is then validated against a variety of experimental data in literature.