Analytical models for electroosmotic consolidation of layered soil systems considering the boundary effects of horizontal electrodes

Abstract

The pore water can usually flow through the horizontal electrodes, resulting in the top sand layer and the bottom unelectroosmotic layer inevitably affecting the consolidation process of the electroosmotic layer. However, the traditional assumption of the fully drained or undrained electrode boundaries is unable to reflect these boundary effects. In this study, one-dimensional analytical models for electroosmotic consolidation of the layered soil systems considering the boundary effects of horizontal electrodes are proposed. The solutions for the models are derived using the separate variable method and Laplace transform method. The rationality of the one-dimensional model is also illustrated by comparing it with the results produced by the two-dimensional model and the accuracies of the solutions are verified through a series of analytical and numerical validation examples. Parametric studies are conducted to investigate the effects of the sand layer and the unelectroosmotic layer on the consolidation process. Results show that both the sand layer and the unelectroosmotic layer may significantly delay the consolidation progress. The time factor corresponding to 90% average degree of consolidation (T_{v_90%U*}) can increase by over 1.5 times in comparison with the model without a sand layer when the permeability coefficient ratio of the subsoil to the upper layer reaches 10. The delayed effect is particularly pronounced when the thickness of the unelectroosmotic layer with higher compressibility is relatively larger, potentially resulting in a tenfold or even greater increase in T_{v_90%U*}.