Modelling of compacted bentonite swelling accounting for salinity effects

• Published in: Engineering geology 2017-06, Vol.223, p.48-58
• Main Authors: Navarro, Vicente, Yustres, Ángel, Asensio, Laura, la Morena, Gema De, González-Arteaga, Jesús, Laurila, Teemu, Pintado, Xavier
• Format: Article
• Language: English
• Subjects: Bentonite swelling; Destructuration; Electrochemical potential; Modelling; Salinity effects
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2017.04.016

This paper presents a formulation to incorporate the influence of water salinity on the swelling behaviour of a MX-80 bentonite into previously developed hydro-mechanical models that can reproduce swelling under dilute conditions. The effects of salinity on macro- and microstructural water chemical potentials were introduced. In addition, a description of solute transport was included to characterise the evolution of the system's salinity. A simplified geochemical model was adopted to idealise the geochemical complexity of bentonite. In addition, the modelling of the destructuration process that occurs during swelling was modified to account for the effect of salinity. The formulation was implemented in a multiphysics partial differential equation finite element solver, and the numerical model was used to simulate several vertical free swelling tests with feed water of different salt contents (deionised, 10, 35 and 70g/L). The results demonstrate that even though the model can be developed further, it represents a significant improvement over models that do not account for the effects of salinity. •Influence of water salinity on the swelling behaviour of a MX-80 bentonite•Simplification of the bentonite geochemical complexity•Macro- and microstructural water equilibrium (equal chemical potentials)•Improvement over models that do not account for the effects of salinity