Mechanism of electro-osmotic chemical for clay improvement: Process analysis and clay property evolution

Electro-osmotic chemical methods were applied in a series of geotechnical studies in which various solutions were injected into clay samples, increasing the undrained shear strength of the clay. Such methods resulted in a series of phenomena and in clay property evolution. In this study the current, temperature, settlement, drainage volume, and electrical potential distribution during the electro-osmotic experiments were monitored as process data, and the electrical conductivity in clay, calcium content, pH, water content, and undrained shear strength after the electro-osmotic chemical experiments were measured as clay property evolution data. Based on the process data, clay property data, and relevant theories, the mechanism of clay reinforcement with electro-osmotic chemicals was comprehensively explained. The development of an electro-osmotic permeability coefficient difference and the permeable drainage boundary condition resulted in a negative pore water pressure distribution shaped as an arch, which resulted in the water content having the same distribution and induced settlement. Because of the gathering of Ca2+ and H+ near the anode, a chemical cement reaction occurred near the cathode. The electrical potential gradient near the anode was lower than that near the cathode. Because of the chemical cement reaction between Ca2+, OH−, and SiO32−, the undrained shear strength near the cathode was much higher than that near the anode. In addition, a coupling analysis of the electro-osmotic chemical process and clay property evolution is presented at the end of the discussion.