Suction controlled triaxial apparatus for saturated-unsaturated soil test

A suction controlled triaxial apparatus has been developed in Geotechnical Engineering Laboratory of Kyushu University. The apparatus has been designed to obtain mechanical properties of unsaturated soil such as shear strength and stiffness, as well as hydraulic properties of unsaturated soil, i.e. Soil Water Retention Curve (SWRC) by measuring change of drained water volume during applied matric suction. Not only for unsaturated condition, this apparatus can be also used to conduct conventional test on saturated soil. This paper focuses on the performance of the apparatus, by performing a series of multistage test on unsaturated soil under drying and wetting path. The hydraulics and mechanical properties of unsaturated soil are presented and discussed.