Apllication of Electrokinetic Phenomena in Geoengineering and Geoenvironmental

The water content of fine-grained soils is a fundamental physical characteristic of the material and has a large impact on the material’s strength. Controlling water in fine-grained soils is therefore of paramount importance but presents recurrent problems owing to the very low hydraulic permeability of the materials. Electroosmosis can transport water through fine grained soil at up to four orders of magnitude faster than hydraulic techniques. However, in medium to coarse-grained soils it provides a less effective transport mechanism than conventional hydraulic flow because the higher hydraulic permeability of these materials permits backflow in response to the pressure differentials built up by electroosmosis.

In 1939, Casagrande (1952) demonstrated that applying electrokinetics to fine-grained soils with high water contents resulted in an increase in the effective stress within the soil through the generation of negative pore water pressures. He used this to increase soil shear strength and thus stabilise steep railway cuttings. Since the initial work of Casagrande, there have been a number applications of electrokinetic phenomena in field projects including: improvement of excavation stability, electrochemical hardening, fine-grained soil stabilisation, consolidation, densification and electro remediation (Pamukcu, 1996).