Pore pressure model and undrained shear strength of soft clay under cyclic loading

The developments of pore pressure and axial deformation of undisturbed samples are studied by cyclic axial shear tests. A model for predicting the evolution of pore pressure under cyclic shear loading is proposed. The dynamic shear strength under undrained cyclic shear conditions is determined, and the degradation characteristics of undrained monotonic shear strength after cyclic loading are also analyzed. The effects of confining pressure and the frequency of cyclic loading on dynamic shear strength are studied. Studies show that, under a definite axial strain, the cyclic numbers decreases notably with the increase in cyclic stress ratio. Besides, the static undrained shear strength is degraded with the increase in cyclic stress ratio.