Influence of electro-osmosis activation time on vacuum electro-osmosis consolidation of a dredged slurry

Combining vacuum preloading with electro-osmosis of a dredged slurry is a significantly effective technology for ground improvement. Despite extensive research, the mechanism of vacuum preloading combined with electro-osmosis is still not properly understood, especially regarding the optimum electro-osmosis activation time. In this study, laboratory tests were performed to confirm the influence of electro-osmosis activation time on vacuum electro-osmosis consolidation of a dredged slurry. A total voltage of 12 V was used in five tests with different electro-osmosis activation times. During the combined process of vacuum preloading and electro-osmosis, the vacuum pressure, electric current, and volume of extracted water were monitored. The water content and shear strength were measured after the tests. The results indicated that electro-osmosis was activated when the degree of consolidation for the soil reached 60%. Thus, this approach can significantly promote the effectiveness of soil consolidation. The shear strength distribution along the depth was much more uniform in all tests with electro-osmosis. The shear strength decreased linearly with increasing distance from the anode rows, but sharp increases occurred near the cathode row (or prefabricated vertical drains).