A modified bounding surface plasticity model for sand

A modified bounding surface plasticity model developed within the critical state soil mechanics framework is presented. Herein a modified version of the Dafalias and Manzari (2004) model is proposed, specifically de-veloped to improve its capability to reproduce the cyclic behaviour of sands under different strain levels adopting a unique set of constitutive parameters. The proposed modified version of the model includes a thermodynamically consistent isotropic hyperelastic formulation for the very small strain range, which realisti-cally reproduces the nonlinear stress dependence of the elastic stiffness. Furthermore, modified versions of the plastic modulus and dilatancy laws are introduced leading to a more realistic small to medium strain range cy-clic behaviour, while preserving the original good predictive capability for monotonic and cyclic loading at large strains. The model response is illustrated by comparison with experimental data over a wide range of void ratios and stress states.