Deformation of intact soft clay under principal stress rotation with effect of intermediate principal stress

Abstract

Undrained shear tests of principal stress rotation on Hangzhou intact soft clay,in which the average principal stress,the coefficient of intermediate principal stress and the shear stress were kept constant,were conducted by using a hollow cylinder apparatus(ZJU-HCA).The reliability analysis of stress paths and strain components was carried out.Thereafter,based on the reliability analysis,the influences of pure principal stress rotation on different strain components and generalized shear strain as well as shear modulus were discussed.In all tests,the coefficient of intermediate principal stress was set to 0.5,and the test results show that the value of radial strain is very small so can be considered as negligible.The development of axial strain is opposed to that of the circumferential strain.The torsional shear strain is dominant when compared with other components.If low shear is stress applied,the corresponding strains in pure principal stress rotation tests are very small.The influence of shear stress reveals that the greater the shear stress,the higher the strain components will be.And the generalized shear strain is better to be considered only under high shear stress level.Shear modulus in pure principal stress rotation tests gradually reduced with a spoon shape.It is proved that the previous principal stress rotation and the high shear stress have significant effect on the deformation of intact soft clay due to subsequent rotation of principal stress axes.