A micro-inspired perspective on the constitutive modelling of clays

Clays are ubiquitous in geotechnical and environmental engineering applications and understanding their complex mechanical behaviour is essential for designing and constructing safe and efficient structures. Over the years, numerous constitutive models have been developed to describe their mechanical behaviour, but only few of them were formulated explicitly accounting for the complex microstructural behaviour of these materials. The aim of this paper is providing an overview of some recent advances in micro-inspired constitutive modelling of clays. After a review of multi-scale experimental evidence and its possible interpretation and generalisation in terms of internal variables controlling the mechanics of clayey soils, two examples of constitutive models are proposed, both developed in the framework of Thermodynamics with Internal Variables. This theoretical environment proves to effectively allow the development of constitutive models that not only respect the fundamental principles of thermodynamics, but also directly benefit from our understanding of the complex micromechanics of clayey soils.