Compacted bentonite hydro-mechanical modelling when interaggregate porosity tends to zero

A formulation is proposed for reproducing the hydro-mechanical behaviour of compacted bentonites as interaggregate porosity becomes negligible. In that case, the model assumes the bentonite deformability to be controlled only by the microstructural modelling level in a double porosity approach. Hence, the bulk stiffness of the system is defined by the relationship between the microstructural void ratio and the thermodynamic swelling pressure, requiring no additional parameters to simulate the overall behaviour. An experimental study has been conducted to check the conceptual consistency of the formulation, with favourable results. The quantitative potential of the model has also been satisfactorily verified by numerical simulation of the tests carried out in this study. A displacement-based finite-element model developed for double porosity systems has been modified to run the simulations. The proposed formulation has been implemented using a simple strategy that can be easily replicated for similar numerical models. Both the simulation capabilities and the computational cost efficiency of the proposed formulation confirm its practical interest.