The effects of electroosmotic field treatment on the soil properties of a soft sensitive clay

Abstract

A field test was undertaken to assess the effectiveness of the electroosmotic strengthening of the soft sensitive (Champlain Sea) clay in the Gloucester Test Fill site by using specially designed copper electrodes to improve treatment efficiency. Tube samples, 127 mm in diameter, were recovered before and after field treatment for detailed laboratory tests. Isotropically consolidated undrained triaxial tests with pore-pressure measurements were performed. It was found that the failure envelope after treatment was significantly higher than the initial envelope, indicating that the strength in terms of effective stresses increased. Consolidation tests showed that, as a result of treatment, the preconsolidation pressure increased from 53 to 98 kPa. The soft clay is virtually "overconsolidated" by the process. Additional effects of electroosmosis on the properties of the soft clay are the increase in plasticity, carbonate content, and salinity and the decrease in sensitivity. There is, therefore, a general improvement in soil properties after treatment, both in terms of total and effective stresses. Key words: electroosmosis, soft sensitive clay, failure envelope, sensitivity, preconsolidation pressure, pH value.