A numerical model is developed for the design and analysis of electroosmotic consolidation in soft soil. Finite difference method is used for estimating ground settlement increase in soil shear strength induced by electro-osmosis. A well documented full-scale field test is analyzed using the numerical model for verification. Sensitivity analysis is conducted to address the uncertainty of the model. The results from the numerical analysis are consistent with the measurement of the ground settlement and soil undrained shear strength after the field test. The results indicate that the soil improvement induced by electroosmosis is sensitive to the electroosmotic conductivity and the voltage distribution in the soil.
Soil improvement by electro-osmosis involves applying a direct current (dc) voltage across electrodes embedded in the soil. The dc current drives soil pore water from the anode toward the cathode. If water is permitted to drain at the cathode and prohibited to enter the anode, a non-uniform negative excess pore water pressure will be induced in soil by electroosmosis, which leads to consolidation (Casagrande 1949; Esrig 1968; Wan and Mitchell 1976) and consequently reduction of soil water content and increase in soil shear strength. Furthermore electroosmosis can accelerate dissipation of the excess pore water pressure induced by the surcharge pressure. Ersig (1968) proposed analytical solutions to calculate the excess pore water pressure in a onedimensional uniform electric field in which the electric field intensity is constant. Wan and Mitchell (1976) derived analytical solutions to calculate the excess pore water pressure for the electro-osmotic treatment in a uniform electric field with a surcharge pressure. Shang (1998) developed an analytical solution for the electro-osmotic consolidation in a uniform electric field in anisotropic soil with a surcharge pressure. The author estimated the undrained shear strength based on estimated preconsolidation pressure due to the electroosmosis and surcharge pressure.