A case record of electroosmotic consolidation of soft clay with improved soil–electrode contact

Abstract

Electroosmotic (e.o.) consolidation of clays has been known in geotechnical engineering for many decades but is in fact seldom used. The analysis of published data from case records indicates that the power losses at the soil–electrode contact constitute a major problem for the field application of e.o. consolidation. A laboratory study, where field conditions were reproduced, has demonstrated the efficiency of a chemical treatment at the electrodes to enhance potential transfer to soil. The chemical treatment was evaluated in a large field demonstration test where over 700 m3of clay was consolidated by electroosmosis. The paper describes the site, the field setup, and the results and analysis of the monitoring during the 48 days of the e.o. treatment. The results of the post-treatment geotechnical investigation after 12% of clay compression due to electroosmotic consolidation are also presented and discussed. These results confirm that soft clay deposits can be successfully treated by e.o. consolidation, at a competitive cost compared with other alternatives, when power losses at the soil–electrode contact are controlled.Key words: case record, electroosmosis, soft clays, consolidation, soil improvement.