How to connect two scales of behaviour in constitutive modelling of geomaterials

Localised failure of geomaterials involves deformation at two scales: a narrow localisation zone and the surrounding bulk. The behaviour associated with both scales should be properly taken into account in the development of constitutive models. This article presents a general constitutive modelling framework to connect these two scales, each of which is associated with a different stage of the material behaviour. It is demonstrated how this approach can be applied to any geomaterial model and how it could help obtain solutions independent of the spatial discretisation in numerical analysis.