Overview and interpretation of stress-relaxation of soft clay

Extensive laboratory tests and field observations show that soft clay exhibits significant stress relaxation characteristics. The evolution of pore pressure and stress of soft clays under both 1D and 3D stress relaxation tests was first studied based on published data from the view of the influence of strain rate and strain level prior to the relaxation phase. The relationship between parameters related to stress relaxation and liquid and plastic limits were discussed. Then, the stress relaxation behavior of soft clays under complex stress conditions was also analyzed. Furthermore, based on stress relaxation curves on double logarithmic plane, the stress relaxation coefficient was originally proposed, and an analytical solution of 1D stress relaxation was derived, which unified three time-dependent characteristics with their key parameters. Finally, the stress relaxation characteristics of soft clay were investigated from the aspect of stress-dilatancy of Hong Kong Marine clay under triaxial extension and stress relaxation conditions with some typical stress-dilatancy equations.