Research on the small strain stiffness behavior of soft clay under complex stress path

A series of principal stress rotation tests were carried out on soft clay with a hollow cylinder apparatus equipped with high censers. Stress paths with various principal stress directions were conducted. The influence of intermediate principal stress parameter (b) and shear stress level (q) was taken into consideration. The effect of stress rotation on the small strain stiffness of soft clay was studied in particular. The test results indicated that, the stiffness of soft clay was affected by the magnitude of strain under complex stress condition. The stiffness was relatively higher when strain was smaller than 0.01%, and the stiffness decreased quickly during 0.01%~0.1%. The influence of shearing direction on the small strain stiffness was unobvious, while the influence of b was obvious.