Undraind Non-coaxial Deformation Behavior of Soft Clay Subjected to Principal Stress Rotation

In this paper a series of undraind principal stress rotation tests were carried out on intact soft clay with an automatically hollow cylinder apparatus, the non-coaxial behavior of soft clay was invested in particularly. The influence of intermediate principal stress parameter (b) and shear stress level (q) on the non-coaxial behavior was studied. The test results indicated that soft clay behaved non-coaxially under rotational shearing, the non-coaxial angle varied periodically during the principal stress rotation. Obvious strain and pore water pressure was induced by the pure principal stress rotation. It was found that the lower the shear stress, the larger non-coaxiality was induced, but this trend reduced with the increase of shear stress. The effect of b on non-coaxiality of soft clay was not obvious.