Estimating vertical and lateral pressures in periodically structured montmorillonite clay particles

Anais da Academia Brasileira de Ciências

Guillermo A. Narsilio²  David W. Smith¹  Peter Pivonka¹ 

[1] ,The University of Melbourne Civil Engineering Block Department of Civil and Environmental Engineering Parkville,Australia

关键词: clay;    Maxwell tensor;    Poisson-Nernst-Planck equation;    pore-scale;    swelling;    van't Hoff law;    argila;    modelo de Maxwell;    equação de Poisson-Nernst-Planck;    escala de poro;    inchamento;    relação de van't Hoff;   

DOI  :  10.1590/S0001-37652010000100003

来源: SciELO

【 摘 要 】

Given a montmorillonitic clay soil at high porosity and saturated by monovalent counterions, we investigate the particle level responses of the clay to different external loadings. As analytical solutions are not possible for complex arrangements of particles, we employ computational micromechanical models (based on the solution of the Poisson-Nernst-Planck equations) using the finite element method, to estimate counterion and electrical potential distributions for particles at various angles and distances from one another. We then calculate the disjoining pressures using the Van't Hoff relation and Maxwell stress tensor. As the distance between the clay particles decreases and double-layers overlap, the concentration of counterions in the micropores among clay particles increases. This increase lowers the chemical potential of the pore fluid and creates a chemical potential gradient in the solvent that generates the socalled 'disjoining' or 'osmotic' pressure. Because of this disjoining pressure, particles do not need to contact one another in order to carry an 'effective stress'. This work may lead towards theoretical predictions of the macroscopic load deformation response of montmorillonitic soils based on micromechanical modelling of particles.

【 授权许可】

CC BY   
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