Drying response and effective stress in a double porosity aggregated soil

Shrinkage and water retention characteristics of a double porosity compacted soil are studied. Results from a series of suction controlled oedometric drying tests at different net stresses are presented. Water retention curves exhibit a bimodal response which is a characteristic of the double porosity structure of the soil. Validity of the expression proposed by Khalili et al. [Khalili, N., Witt, R., Laloui, L., Vulliet, L., Koliji, A., 2005. Effective stress in double porous media with two immiscible fluids. Geophys. Res. Lett. 32 (15): Art. No. 15309.] for the determination of the effective stress in double porosity media is investigated. It is shown that quantitative predictions of volume change in unsaturated aggregated soils can be made using the effective stress concept.