Constitutive modeling of effects of path-dependent full-strain-range nonlinearity on cyclic behavior of undrained clays

Undrained clays subjected to cyclic loading exhibit significant non-linearity in their stress–strain behavior across a wide range of strain levels, from very small (10 −5 ) to relatively large (10 −1 ) strains. This nonlinear variation of soil stiffness is strongly path-dependent, which can significantly influence cyclic foundation-soil interactions and cumulative responses. This study presents a total stress-based constitutive model that incorporates path-dependent, full-strain-range nonlinearity, using the generalized non-linear (GNL) hardening law and the intergranular strain (IGS) elastic model within the bounding surface plasticity framework. The GNL hardening law captures versatile stress–strain relations at relatively large strains for various loading paths, while the IGS model accounts for path-dependent stiffness degradation in the relatively small-strain range. The proposed model is first evaluated by simulating element test responses of undrained clays, with comparisons to reference models highlighting its improvements. Parameter studies are conducted to examine the influence of path-dependent nonlinearity on cyclic stress–strain relations and the growth rate of cyclic cumulative deformations. Finally, the model is applied in finite element simulations of centrifuge tests on the uplift responses of suction caisson foundations subjected to cyclic loading.