A framework for the behaviour of unsaturated expansive clays

TLDR

It is an extension of an existing formulation developed for unsaturated soils of low activity. The paper presents a framework for describing the mechanical behaviour of unsaturated expansive clays. The extended framework distinguishes a microstructural level where active mineral swelling occurs and a macrostructural level governing major structural rearrangements, and simple coupling assumptions allow reproduction of key unsaturated expansive clay behaviours. Qualitative comparisons with literature data show encouraging agreement between model predictions and experimental results. Key words: capillarity, clay, model, unsaturation, suction, expansive soils.

Abstract

The paper presents a framework for describing the mechanical behaviour of unsaturated expansive clays. It is an extension of an existing formulation developed for unsaturated soils of low activity. The extended framework is based on the distinction within the material of a microstructural level where the basic swelling of the active minerals takes place and a macrostructural level responsible for major structural rearrangements. By adopting simple assumptions concerning the coupling between the two levels, it is possible to reproduce major features of the behaviour of unsaturated expansive clays. Some selected qualitative comparisons between model predictions and experimental results reported in the literature are presented. Despite the simplified hypotheses made, a very encouraging agreement is obtained. Key words : capillarity, clay, model, unsaturation, suction, expansive soils.