Electrokinetic strengthening of a marine sediment using intermittent current

Abstract

An experimental program on electrokinetic strengthening of a marine sediment using intermittent current was conducted on a high-salinity marine clay recovered from a land reclamation site on the Korean coast. The study focused on the use of electrokinetics to enhance the effect of surcharge preloading consolidation to improve mechanical and physical properties of soil. This paper presents the design, execution, and results of the electrokinetic tests performed in a custom-designed electrokinetic cell. The test results demonstrate that electrokinetic treatment combined with preloading consolidation is an effective method of increasing the shear strength and decreasing the water content of the marine sediment beyond that achievable by preloading consolidation alone. For the same consolidation pressure over the identical time period, the increase in the average undrained shear strength of the marine sediment after electrokinetic treatment combined with preloading consolidation was up to 145% greater than that achieved by the preloading consolidation alone. A corresponding decrease in the soil water content of approximately 125% was measured. The power consumption and electrode corrosion are reduced by using intermittent current. The process developed in this research has potential applications in strengthening soft clayey soils at and around foundations of new onshore and offshore structures embedded in marine sediments and for rehabilitation of existing offshore platforms.Key words: marine sediment, electrokinetics, preloading consolidation, soil improvement, soil shear strength, land reclamation.