A thermo-hydro-mechanical constitutive model and its numerical modelling for unsaturated soils

Abstract

A thermo-hydro-mechanical (THM) constitutive model for unsaturated soils is proposed in this paper based on the existing models. The influences of temperature on the hydro-mechanical behaviour in unsaturated soils are described in the model. Particularly, the thermal softening phenomenon, i.e. decreases in value of the pre-consolidation pressure and in critical value of the suction of the SI (suction increasing) curve with heating process, is quantitatively modelled by using the experimental data and previous work [J. Geotech. Eng. ASCE 116 (12) (1990) 1765; J. Geotech. Eng. ASCE 116 (12) (1990) 1778; Can. Geotech. J. 25 (1988) 807; Int. J. Numer. Anal. Meth. Geomech. 22 (1998) 549; Can. Geotech. J. 37 (2000) 607; Characterisation and thermo-hydro-mechanical behaviour of unsaturated Boom clay: an experimental study. Thesis Doctoral 1999, Technical University of Catalonia (UPC), Barcelona, Spain]. Numerical modelling of the proposed THM model has also been implemented within the finite element code LAGACOM. Finally, the comparisons of the results obtained from the numerical modelling of the constitutive behaviour with existing experimental results show that the present model can simulate the thermo-hydro-mechanical behaviour in unsaturated soils with satisfaction. Some other numerical results given in the paper also validate the versatility and applicability of the present constitutive model.