Elasto-viscoplastic modeling of Osaka soft clay considering destructuration and its effect on the consolidation analysis of an embankment

A numerical modeling of Osaka soft clay was carried out using an elasto-viscoplastic constitutive model. The effect of destructuration, demonstrated by the shrinkage of the yield and the overconsolidation boundary surfaces and the strain-dependent elastic shear modulus, were studied through a comparison of the simulations with the experimental results of undrained triaxial compression tests. Although consideration of the structural degradation in the modeling of soft soil behavior leads to a substantial improvement, in terms of strain softening and post-peak responses, the strain-dependent shear modulus was introduced to reproduce more precise behavior, particularly before the peak stress. In order to evaluate the effect of these two aspects in a boundary value problem, a two-dimensional consolidation analysis of an embankment construction on a soft clay layer was conducted for three different cases. The deformations and the excess pore pressure responses for each case were presented and discussed. The strain localization, the consequent large ground displacement, and the temporary increase in pore pressure during the consolidation were observed in the cases with structural degradation. Considering the strain-dependent shear modulus, however, larger strain localization and displacement were predicted even in the early stages of loading.