The effect of the electric field intensity on electro-cementation of calcareous sand was studied via the large model tests and the electric field analyses. In the experiments, the model caissons were embedded in calcareous sand and a dc intermittent electric field was applied via a central electrode. After 7 days of treatment the pullout resistance of the caisson model increased up to 190 % and generated significant soil cementation. The electro-cementation was found closely related to the electric field intensity, which is determined by the applied voltage, electrode layout and soil electrical conductivity. Furthermore the results indicate that the effectiveness of the electrokinetic treatment is directly associated with the electric field intensity surrounding the caisson. This study demonstrates the relationship between the electric field intensity and electro-cementation between calcareous soil and foundation elements, which serves as the fundamental principle in engineering design.
Calcareous soils are encountered in many offshore oil reserves and pose challenges to offshore foundations throughout the world such as in Australia, India, Saudi Arabia, and the Caribbean (Murff, 1987; King and Lodge, 1988). Calcareous soils typically consist of over 50% calcium carbonate, derived from skeletal remains of marine organisms. The calcareous soil is highly compressible and naturally cemented. The installation of offshore foundations generates disturbance to the soil, destroys the cementation bonds and results in low skin friction between the soil and foundation elements (Dolwin et al., 1988).
Suction caissons have been used as anchors for floating platforms in many sites including the North Sea, Brazil, Gulf of Mexico, Timor Sea, West Africa, and West of Shetlands (Ehlers et al. 2004). A suction caisson typically comprises a steel cylinder with a sealed top and open bottom. A major advantage of suction caissons is their high uplift capacities relative to their weights.
