Analysis of a Field Experiment to Assess the Performance of an Anisotropic Plasticity Model for Cohesive Soils

摘要

A recently conducted field experiment is used to assess the significance of initial and induced anisotropy on the response of a layered soil system consisting of Ko-consolidated clay layers with different over-consolidation ratios. The soil is subjected to the weight of a trial soil embankment. To assess the role of soil anisotropy in the observed response of the layered soil system, a detailed nonlinear finite element analysis using a fully-coupled effective stress approach is conducted. The clayey soils are modeled by using two different constitutive models: an anisotropic soil plasticity model (SANI Clay) and the well-known isotropic clay plasticity model (modified CAM Clay). Both models were calibrated based on the laboratory and in-situ test data available for the soils. The results of the numerical simulations indicate that the proper modeling of initial and induced anisotropy has an important effect on the computed settlement of the layered soil and on the deformation of the soil embankment. It is observed that while the finite element simulations using SANI Clay closely reproduce the observed settlement of the soil embankment, the modified Cam Clay model underestimates the ultimate settlement of the embankment. There are also significant differences in the computed lateral displacements using the two constitutive models. The effect of soil anisotropy on generation and dissipation of excess pore pressures within the clay layers is also investigated and the results are presented.