Numerical Simulation of Tortuosity Effect on the Montmorillonite Permeability

Abstract

This study analyzed the association between the coefficient of permeability of clayey sealing materials and their tortuosity. Montmorillonite was selected because it is used as a barrier in geo-environmental projects and its sensitive structure results in wide variations in permeability when in contact with pore fluids. A DEM code was developed by considering mechanical force, diffuse double layer repulsion, and Van der Waals attraction as the inter-particle interaction. The coefficient of permeability was calculated by simulating a consolidation test and the DEM simulations were compared with experimental data. The results showed that the coefficient of permeability decreased as the void ratio decreased. At the same void ratio, there was a deviation between the coefficient of permeability for clay-electrolyte systems caused by the micro-fabric and variations in tortuosity. Micro-fabric evolution during loading showed that increasing the stress state caused reorientation of the particles perpendicular to the direction of loading and increased anisotropy of the particle orientation, increasing the tortuous flow path.