Examination on Time-Dependent Soil Models in One-Dimensional Consolidation

This paper reviews the performance of two time-dependent constitutive models in predictions of one-dimensional consolidation. The Soft-Soil Creep model [1] is an example of an elastic-viscoplastic formulation that incorporates a time-dependent state variable to estimate viscoplastic deformation. We show that the SSC model is equivalent to the isotache formulation proposed by Imai [2], as both are based on a unique relationship between stress, void ratio and the viscoplastic component of void ratio rate. Simulations of 1-D consolidation confirm that both models represent Hypothesis B behavior, where the axial strain at the End of Primary (EOP) consolidation is dependent on the depth of the clay layer. The effects of specimen thickness and the phenomenon of pore pressure increase at the start of consolidation are discussed in detail. Our interpretation highlights the importance of assumptions regarding the initial strain rate on the behavior observed at different scales under a given applied increment of loading