Quantitative modelling of granular soils considering density and pressure effects

Hypoplasticity is a relatively new framework for constitutive modelling of granular materials. A revised version of the hypoplastic model for granular soils originally formulated by Gudehus and Bauer is proposed. The original model can qualitatively reproduce the density-dependent behaviour of sand-like granular materials, including shear dilation and strain softening. But it is not good enough for quantitative prediction of stress-strain responses, particularly when the material is very dense. The revision is made by introducing a scalar factor in the tensor-valued function, which enhances the capability of the constitutive equation in capturing various stress paths. A stress-transformation technique is employed in the revised model to improve the predictions of the material response under three-dimensional stress condition. Numerical results are presented with the experimental data to demonstrate the better performance of the revised model.