Fem validation of a double porosity elastic model for consolidation of structurally complex clayey soils

Laboratory consolidation of structured clayey soils is analysed in this pap er. The research is carried out by two different methods. The first one tre ats the soil as an isotropic homogeneous equivalent Double Porosity (DP) me dium. The second method rests on the extensive application of the Finite El ement Method (FEM) to combinations of different soils, composing 2D or full y 3D ordered structured media that schematically discretize the complex mat erial. Two reference problems, representing typical situations of 1D labora tory consolidation of structured soils, are considered. For each problem, s olution is obtained through integration of the equations governing the cons olidation of the DP medium as well as via FEM applied to the ordered scheme s composed of different materials. The presence of conventional experimenta l devices to ensure the drainage of the sample is taken into account throug h appropriate boundary conditions. Comparison of FEM results with theoretic al results clearly points out the ability of the DP model to represent cons olidation processes of structurally complex soils. Limits of applicability of the DP model may arise when the rate of fluid exchange between the two p orous systems is represented through oversimplified relations. Results of c omputations, obtained having assigned reasonable values to the meso-structu ral and to the experimental apparatus parameters, point out that a partiall y efficient drainage apparatus strongly influences the distribution along t he sample and the time evolution of the interstitial water pressure acting in both systems of pores. Data of consolidation tests in a Rowe's cell on s amples of artificially fissured clays reported in the literature are compar ed with the analytical and numerical results showing a significant agreemen t. Copyright (C) 2000 John Wiley & Sons, Ltd.