Theoretical analysis and experimental verification of large deformation electro-osmosis consolidation treatment of dredged slurry

Abstract

Electro-osmosis (EO) can be used to rapidly treat large areas of dredged slurry. At present, the theory of electro-osmosis consolidation (EOC) needs to be further developed to fit actual dredged slurry treatment scenarios. In this study, governing equations of EOC considering the large deformation constitutive relationship were derived with excess pore water pressure (EPWP) as a variable, and a concise EOC model was established for dredged slurry. Together with boundary conditions and initial conditions, the numerical method was adopted to obtain the finite difference solution for the EOC model. Then, EO experiments with different voltage stages were conducted using a self-designed and large-diameter EOC device, where the variations in current, drainage volume, EPWP, water content and vane shear strength were measured. Moreover, the phenomena of soil cracks, heat release, and electrode corrosion as well as the formation of Fe(OH)3 were recorded during the EO process. Additionally, nonlinear variation laws for effective stress, hydraulic permeability coefficient (HPC) and electro-osmosis permeability coefficient (EOPC) with void ratio of dredged slurry were obtained through indoor tests, in which a self-designed device for testing EOPC was used. Finally, the correctness of the proposed EOC model was verified by comparison with the results of the experiments and Esrig's analytical solution considering the small-strain constitutive relationship, where the consolidation characteristics were analyzed. In conclusion, the large deformation EOC model deduced in this paper could provide a more accurate prediction of the consolidation behavior of dredged slurry.