ABSTRACT
The validity of the relationship proposed by Khalili & Khabbaz (1998) for the determination of the effective stress parameter χ is examined using both shear strength and volume change data. It is shown that quantitative predictions of shear strength and volume change in unsaturated soils can be made using the effective stress principle. The reasons underlying the apparent difficulties in previous investigations of the effective stress in unsaturated soils are highlighted. The incremental form of the effective stress parameter is derived and validated.
