Field test of electroosmotic strengthening of soft sensitive clay

Abstract

A field test was undertaken to assess the effectiveness of electroosmosis in strengthening the soft sensitive (Leda) clay at the Gloucester test fill site. Specially designed copper electrodes were installed to prevent gas accumulation around the electrode and to allow pore water in the soil to flow out from the cathode without pumping. The variation of settlement, shear strength, and voltage distribution during treatment was measured, and tube samples were recovered before and after treatment for laboratory tests. The results of field vane tests at different locations within the treated area and at different times indicate that the undrained shear strength increased uniformly by approximately 50% for a period of 32 days throughout the depth of the electrodes. Concurrently, an average surface settlement of 50 mm was achieved. The total power consumption was less than 1% of the total project cost, indicating that the design of the treatment system was efficient. It is evident, therefore, that substantial increase in strength as well as general improvement in soil properties may be achieved by this improved version of electroosmosis. The elimination of pumping improved the economy of the process considerably. It is hoped that the process may receive wider application as a result of these improvements. Key words: electroosmosis, electrode, polarity reversal, Gloucester test fill, soft sensitive clay, uniformity of treatment, power consumption.