Effect of soil layering and interface resistance on electro‐osmotic consolidation of layered soils: A Green's function approach

Abstract

During electro‐osmotic consolidation, effective voltage attenuation induced by the increasing interface resistance is an important phenomenon, which significantly decreases consolidation effectiveness. This paper presents an analytical model for one‐dimensional electro‐osmotic consolidation in layered soils with horizontal graphite electrodes considering effective voltage attenuation. The mathematical model is characterized by time‐dependent source term and discontinuous interface flux. New variables are introduced to homogenize the discontinuous interface flux and Green’s function method is used to solve the new nonhomogeneous governing equations with nonhomogeneous boundaries. Several verification examples are conducted using the existing analytical solution and numerical results. Parametric studies indicate that electro‐osmotic consolidation of layered soils cannot be accurately simulated by equivalent homogeneous soil, whether effective voltage attenuation is considered or not. Furthermore, the backflow phenomenon may occur due to effective voltage attenuation, while it may disappear when the anode is placed in the low‐permeability layer. In addition, the optimal arrangement of electrodes in layered soils is also investigated. When the ratio of the thickness of low‐permeability layer to high‐permeability layer is about 1/3, installing the cathode in the low‐permeability layer can improve the electro‐osmosis effect up to two times, compared with installing the anode in the low‐permeability layer.