Consolidation of Fissured clays

Abstract

A numerical model for consolidation of fissured clays, on the basis of the double-porosity concept, is presented. As applications of the model, two numerical examples are analysed: a one-dimensional soil column, and a strip loading on a two-dimensional medium of a fissured clay. It is shown that, in comparison to an equivalent single-porosity model, the settlement in a double-porosity medium is delayed due to the slow dissipation of excess fluid pressure in the clay matrix. In addition, three distinct time periods are identified in the consolidation of a fissured clay. The characteristic of each period are discussed and the parameters affecting these periods are highlighted. Moreover, it is shown that the Mandel–Cryer effect, which is often discussed in relation to consolidation of soils treated as single-porosity material, may not develop in fissured clays. Nous présentons un modéle numérique pour la consolidation des argiles fissurées sur la base du concept de double porosité. En applications du mod&acuate;le, nous analysons deux exemples numériques: une colonne de sol unidimensionnelle et une charge en bande sur un support bidimensionnel d'argile fissurée. Nous montrons que, en comparaison avec un modéle équivalent à une seule porosité, le tassement du support &grave double porosité est retardé en raison de la lenteur de la dissipation de la pression liquide excessive dans la matrice d'argile. De plus, nous identifions trois périodes de temps distinctes dans la consolidation d'une argile fissurée. Nous examinons les caractéristiques de chacune et nous soulignons les param&acaute;tres qui affectent ces périodes. En outre, nous montrons que l'effet Mandel–Cryer qui est souvent discuté dans un contexte de consolidation de sols traités en tant que matiéres &grave une seule porosit&acaute;, pent ne pas se développer dans les argiles fissurées.

A stable meshfree method for fully coupled flow-deformation analysis of saturated porous media

“…The pore water pressure deviation from the analytical solution near the impervious base of the layer is due to the effect of the truncated boundary. A similar deviation of the numerical results from the analytical solution was reported in [45] in the finite element analysis of the problem.…”

Hydromechanical behaviour of a heterogeneous compacted soil: experimental observations and modelling

“…Probably this concept was first introduced by Barrenblatt et al (1960) (as quoted in Ghafouri & Lewis, 1996) to simulate flow through rigid, fissured porous media and it was later enlarged to consider the coupling between fluid flow and soil deformation (e.g. Aifantis, 1980;Wilson & Aifantis, 1982;Gens et al, 1993;Khalili et al, 1999;Callari & Federico, 2000). Here, the formulation developed in Sánchez (2004) is adopted.…”

Coupling effects in double porosity media with deformable matrix

“…Within the context of the theory of double porosity, flow and deformation in fissured clays may be expressed as [ Khalili and Valliappan , 1996; Khalili et al , 1999; and Pao and Lewis , 2002], in which, describes the deformation field within the fissured clay, and and describe the flow of fluid within the clay matrix and the fissure network, respectively. α 1 and α 2 are the effective stress parameters, and a 12 and a 21 are the coupling terms ensuring the deformation compatibility between the two pore systems at a microscopic level.…”