A microstructure-based constitutive model for the hydro-mechanical coupling in compacted clay/sand mixtures

In order to describe the hydro-mechanical behaviour of compacted expansive clay, in the present work, a microstructure-based constitutive model was elaborated based on the following assumptions: (i) the soil porosity can be divided into two levels: microstructural and macrostructural levels; (ii) the plastic deformation correspond to the collapse of the macrostructural porosity. The parameters of the model were calibrated using results from suction-controlled oedometer tests performed on a compacted clay/sand mixture. These parameters were then used to simulate the swelling pressure generated when wetting the soil mixture under constant-volume conditions. Comparison between the modelling and the experimental results showed that the model satisfactorily reproduced the relationships between the suction and the generated swelling pressure, as well as the changes in volumetric water content.