Enriching constitutive models with meso-scale behaviour: a thermodynamics-based formulation and examples

Abstract

A generic approach to encapsulating meso scale details and their associated dissipative mechanisms in constitutive models for geomaterials is presented. The focus is the explicit meso-macro link as the basis for developments of constitutive models. These links are usually missing in constitutive modelling of geomaterials, leading to incorrect description of post-localisation behaviour at the constitutive (material) level. In other words, the classical definition of material behaviour associated with a unit volume element, based on conditions of homogenous deformation, ceases to exist once localised failure occurs. Such localisation issues can and should also be dealt with at the constitutive level. The proposed generic thermodynamics-based formulation to integrate meso scale behaviour of localisation band in constitutive models provides a way to correctly connect meso and macro scales so that post-localisation behaviour can be correctly described at the constitutive level. Examples on onset of localisation and post-localisation behaviour are used to demonstrate key features and benefits of the proposed approach.