Abstract：The triaxial tests of Nanyang unsaturated expansive soil are carried out under four kinds of stress paths，that is isotropic loading tests at various controlled suction，shrinkage tests at various controlled net mean stress，swelling tests at various controlled net mean stress and drained shear tests under controlled cell pressure and suction. Many meaningfull results are obtained. The yield behaviour under isotropic loading of expansive soil can be described by the LC curve，The yield suction of shrinkage test decreases as the net mean stress increasing. The friction angle under unsaturated state is close to that under saturated condition. The total cohesion increases with suction. The water content changes linearly with the net mean stress at isotropic loading test and triaxial shear test. The relationship between water content and suction is also linear under shrinkage test and swelling test.
