Undrained cyclic shear behaviour of normally consolidated clay subjected to initial static shear stress

A series of undrained cyclic triaxial compression tests has been performed on a high plasticity marine clay. Testing was performed using various combinations of initial static and subsequent cyclic shear stress on isotropically and anisotropically consolidated specimens. Additionally, monotonic triaxial compression and extension tests were also performed on the same clay with the same initial condition. The cyclic shear strength was considered first, and then, the accumulated shear strain was investigated related to the effective stress ratio at the peak cyclic stress. Based on the experimental results, a semi-empirical model is proposed for evaluating the development of pore pressure and residual shear strain during cyclic loading. The model successfully explains the behaviour of clay subjected to various magnitudes of initial static and subsequent cyclic shear stresses.