Swelling and mechanical erosion of MX-80 bentonite: Pinhole test simulation

Comparison of the hydrogeochemical and mechanical behaviours of compacted bentonite using different conceptual approaches

“…Regarding the formulation of the conceptual model of the microstructural behaviour, the constitutive equation that links the microstructural void ratio (em) and the chemomechanical variables is given in the form: With regard to the water flow, a van Genuchten retention curve (van Genuchten, 1980) was used to define the variation of the macrostructural degree of saturation SrM in relation to the macrostructural suction sM (Navarro et al, 2015b Fitting parameter of the surface state that defines the micro and macrostructural interaction Navarro (2016) Parameter Definition Reference αi Material parameter of the elastic stiffness for changes in the net mean stress Hoffmann (2007) αm Fitting parameter of emC Navarro (2015) αSp Material parameter used to define κS. Dimensionless Alonso (2011) αSS Material parameter used to define κS.…”

“…Fitting parameter of the surface state that defines the micro and macrostructural interaction Navarro (2016) κio Material parameter of the elastic stiffness for changes in the net mean stress Hoffmann (2007) κm Microstructural stiffness parameter Navarro (2015) κSo Material parameter of the elastic stiffness for changes in suction Alonso 2011κS (s,p) Elastic stiffness for changes in suction evaluated at macrostructural suction s and net mean stress p. Alonso (2011) λ(0) Slope of the virgin compression curve for saturated conditions Alonso (2011) v Poisson's ratio Alonso (2011)…”

“…In the Mc model, a complete elastoplastic constitutive model (Navarro et al, 2013(Navarro et al, , 2014 was chosen based on the Barcelona Expansive Model (BExM) (Alonso et al, 1999;Sánchez et al, 2005), although it includes differentiating elements. First, the model Mc includes a formulation of the water exchange kinetics between micro-and macroporosities that considers the chemical potential difference between both porosity levels (Navarro et al, 2016). The model also uses a constitutive model of the behaviour of the microstructure that is based on the interpretation of retention curves at high suction values (Navarro et al, 2015) and incorporates an alternative definition of the interaction function between the micro-and macrostructural strains to consider the free swelling phenomena and the effect of the salinity of the saturating water (Navarro et al, 2017).…”

“…The description of the mechanical approach of the Mc presented in this work is based on the formulations of Hoffmann et al (2007) and Alonso et al (2011) for the behaviour of the macrostructural level. The conceptual approach for the behaviour of the microstructure and its influence on the macrostructure, has been taken from different works on expansive clays in free swelling conditions (Navarro et al, 2014;Navarro et al, 2015a;Navarro et al, 2016) and that include salinity effects on the microstructural behaviour (Navarro et al, 2017). This appendix only summarises the formulation Fitting coefficient for the mass transfer interaction Navarro (2014) emR Additional microstructural void ratio Navarro (2015)…”

Multiphysics Implementation of Electrokinetic Remediation Models for Natural Soils and Porewaters

“…as Comsol Multiphysics, provide symbolic expressions to define the iteration matrix [41], which improves the convergence behaviour of the model and allows the complexity of the problem to increase while maintaining solution efficiency [42,43]. Thus, in the proposed extended geochemical model, we defined 9 partial differential equations (mass balance in the soil), 16 ordinary differential equations (mass balance in the electrolyte wells), and 11 algebraic equations (chemical speciation), which yields a total of 36 state variables to be solved in each time step.…”