ABSTRACT
ABSTRACT: This paper presents the results from an experimental study on the stress variables governing unsaturated soil behaviour. At the first stage of the study, the case of negative pore pressures and continuous air phase was addressed. A new apparatus was designed and implemented for this purpose. Several tests were performed to verify the common assumption that total stress, pore-air pressure, and pore-water pressure can be combined in two effective stress fields. At the second stage of the study, the case of occluded air was examined. With the operational apparatus, a series of tests was conducted to examine the validity of the axis translation technique at high degrees of saturation. Finally, an osmotically controlled oedometer was set up to investigate whether the effective stress principle for saturated soils is applicable to unsaturated soils at high degrees of saturation.
