On thermodynamically consistent coupling of the Barcelona Basic Model with a hydraulic model for unsaturated soils

Abstract

The Barcelona Basic Model is a mechanical model for unsaturated soils which uses the net stress and suction as independent stress variables. This paper presents a thorough study of its thermodynamically consistent coupling with a hydraulic model. A general framework for poroelastoplasticity formulated in terms of the net stress and suction is developed and then applied to derivation of a consistent hydro–mechanical coupling for the Barcelona Basic Model. The resulting restrictions for description of the hydraulic behaviour are analysed and they are found to be too strict and not completely physically acceptable. It is demonstrated on a model example that the applicability of the resulting hydro–mechanical model is limited. It is concluded that poromechanical models using the net stress and suction as stress variables generally (at least what poroelasticity concerns) should be developed and utilised carefully with respect to the thermodynamical consistency. Otherwise different types of models should be employed for coupled hydro–mechanical modelling.