Study On Strength And Deformation Of Unsaturated Expansive Soils

In this paper, the influence of cycles of drying and wetting on strength and deformation are studied by means of routine direct shear apparatus , triaxial apparatus and light consolidation apparatus which include: the influence of force of constraint on strength, the total stress strength of expansive soils with different saturation degree, the influence of cycles of drying and wetting on the total stress strength, the relation between saturation degree and compression modulus and that between saturation degree and void ratio, the influence of cycles of drying and wetting on the effective stress strength, the relation between saturation degree and generalized suction. As a result, a group of experience equations of strength and deformation of expansive soils are suggested.Moreover, the concept of prestress of unsaturated expansive soils is given in this paper, it is found that the prestress strength is the main difference between unsaturated expansive soils and saturated expansive soils.Finally, two examples were used to analyse the influence of cycles of drying and wetting on subgrade sedimentation and slope stability of expansive soils, the conclusion is given that the influence of cycles of drying and wetting on strength and deformation must be considered to the foundation or structures which consists of expansive soils.