Reappraisal of the anisotropic bounding surface model of small-strain behavior for clays

An anisotropic bounding surface model was developed to simulate the small-strain behavior of compressible Chicago glacial clays, which was obtained from the stress probe experiment. To replicate the observed response of plastic deformation during stress probing, the location of the project origin and the variation of the hardening modulus within the framework of bounding surface plasticity were investigated. A nonlinear anisotropic elastic model obtained from eigenvalues decomposition was introduced to characterize the higher stiffnesses found at very small strain levels. The analysis of plastic strains observed from the experimental data indicated the need to relocate the projection center to the initial stress point for the unloading stress paths. Adding a new distance measure in the stress space to the expression of the hardening modulus for the radial mapping rule can significantly enhance the predictability of the anisotropic bounding surface model in the small-strain region.