Study on the Unsaturated Property of Expansive Soil of the Middle Route of South to North Water Diversion Project in Yuzhou

The effect of matric suction on the shear strength of unsaturated soil can not be ignored,while the expansive soil is a typical unsaturated soil,so studying the effect of matric suction on the shear strength of expansive soil has a great significance to the engineering practice.In this paper,an unsaturated expansive soil test of the Middle Route of South to North Water Diversion Project in Yuzhou is done by the GDS unsaturated triaxial test system.The study has shown that: the total cohesion of expansive soil increases with the increasing of the matric suction,and the increasing is very obvious;matric suction almost has no effects on the effective angle of internal friction;shear strength not only depends on the confining pressure,but also is closely related to the size of the matrix suction,and increases with confining pressure and matric suction increasing.