Electrokinetic improvement of soft clay using electrical vertical drains

The performance of electrical vertical drains (EVDs) is investigated using laboratory tests and a field test. The electrokinetic treatment generates an increase in the soil undrained shear strength of a natural clay soil from London, Ontario, from 3 kPa to over 100 kPa in the laboratory. The soil undrained shear strength in a field test conducted in marine clay increases from between 5 kPa and 13 kPa to between 22 kPa and 39 kPa on average after only five days of electrokinetic treatment using EVDs. It is observed in laboratory and field tests that the water flow generated by electro-osmosis stops shortly after the application of the electric current. The significant shear strength gains of soils observed in the laboratory and field tests are attributed to the reduction of soil water content and increases in Atterberg limits which result from electrochemical reactions.