Abstract:

A hollow cylinder apparatus was used to study failure criteria for Hangzhou intact soft clay under undrained shear stress path with fixed principal stress direction; then the impacts of coefficient of intermediate principal stress, angle of large principal stress direction and pore pressure accumulation on shear strength of clay were emphatically discussed; and shear failure criterion of intact soft clay was proposed. Test results revealed that the coefficient of intermediate principal stress did not affect the variable pattern between stress and strain and stress path; and with the increase of coefficient of intermediate principal stress, the change of shear strength of clay did not show some regularity. The impact of angle of large principal stress direction on the strength of intact soft clay reflected that inherent anisotropy controlled the shear strength of clay. Pore pressure remarkably accumulated in the late period of shearing, which impacted on the performance of the strength of clay. Considering the influencing factors such as coefficient of intermediate principal stress, we used the maximum of generalized shear stress as shear failure criterion of intact soft clay by analyzing changes of generalized shear stress–strain curves.

Key words: coefficient of intermediate principal stress, angle of large principal stress direction, pore pressure accumulation, generalized shear stress, failure criterion