The strength and stiffness of a silty soil in dependence of its saturation were tested using con-ventional and advanced triaxial devices. The tested soil was a low plasticity silty clay from Central Bohemia.
Reconstituted and compacted specimens were tested. The tests on unsaturated soil were controlled using the concept of net stress and suction.
The experiments were aimed at determining parameters for a hypoplastic constitutive model for unsaturated soils and therefore the processing of data and the calibrations used the ef-fective stress concept. In processing the strength data obtained by unconfined compression tests the capillary cohesion concept, and the linear form of extended Mohr - Coulomb strength envelope were adopted.
The re-sults confirmed the good performance of the advanced constitutive model, and also showed the applicability of the capillary cohesion and suction stress concept for the strength testing and interpretation.