Mechanical testing in unsaturated soils

The state-of-the-art report presented herein is aimed at documenting, to the largest extent possible, some of the recent advances in laboratory testing of unsaturated soils for stress-strain-strength-stiffness characterization under suction-controlled isotropic, axisymmetric, and true triaxial stress states. The report is intended to be neither comprehensive nor fully inclusive, offering plenty of room for further discussion on recent refinements and techniques not yet reported in the literature. The main sections in this report are devoted to describing current methods and technologies using cylindrical triaxial systems, including advances in volume change and small- strain stiffness measurements; resonant column/torsional shear systems; other bender element-based systems; and suction-controlled testing under true triaxial stress states. Concluding remarks are included in the last section of the report.