Inclusion of expansive clay behaviour in coupled thermo hydraulic mechanical models

This paper discusses the development of a model for the coupled flow of hea t, moisture and air in expansive clays. In particular, the results of recen t research work on the inclusion of expansive behaviour exhibited by some c lays are presented. Initially, a fully coupled thermal/hydro/mechanical (TH M) simulation of a heating experiment is presented. The observed THM behavi our in unsaturated soil was predicted by the model, with the best correlati on found in the thermal held. The influence of the osmotic potential on the soil via the effect of chemical solute concentration is explored in a non- linear elastic constitutive relationship. The ability of such a model to re present the large strains that call occur during free swelling of expansive soils has been demonstrated. Finally, the representation of the developmen t of irreversible strains within an expansive soil has been investigated vi a a double structure elasto-plastic relationship. The ability of such an ap proach to simulate the accumulation of plastic strains during wetting-dryin g cycles has been shown. (C) 1999 Published by Elsevier Science B.V. All ri ghts reserved.