Constitutive modelling of granular materials with focus to microstructure and its effect on strain-localization

摘要

The paper presents a micromechanically-based constitutive model for frictional granular materials through a fabric (anisotropy) sensitive stress-dilatancy law. A second order tensor is used to describe fabric whose evolution during plastic deformation is chosen to be purely deviatoric and stress ratio dependent. This produces different fabrics at critical state that are consistent with the corresponding critical void ratio. To illustrate the role of fabric and its evolution, model simulations are presented for mixed drained-undrained stress paths within the context of instability. Shear band localization is also discussed with fabric as a controlling dependent variable. Model results suggest that, in an extreme case, a very loose sand could very well display post peak behaviour and shear banding due to fabric.