LABORATORY ASSESSMENT OF THE ELECTRO-OSMOTIC CONSOLIDATION TECHNIQUE FOR URMIA LAKE SEDIMENTS

The electro-osmotic consolidation is a method to improve geotechnical properties of soft clayey soils. The feasibility of electro–osmotically induced consolidation can be examined through the soil coefficient of electro–osmotic permeability (ke) and the electro–osmotic coefficient of water transport (ki). Using an electro-osmotic testing cell, ke and ki parameters were measured in Urmia Lake west coast sediments. Three electric field intensities of 40, 60 and 80 V/m were used and salinity and pH change was monitored in cathode and anode reservoirs during the tests. ke and ki increased when soil void ratio increased. The results showed that increasing applied electric field intensity increased the rate of water pH and salinity change at cathode reservoir. The results for soil hydraulic conductivity (kh) and ke showed that kh is in the range of 10-10 m/s to 10-9 m/s for the range of void ratios between 0.5 to 0.8, respectively, and ke is in the range of 5.5×10-9 to 6.6×10-9 m2/sV for the range of void ratios between 0.72 to 0.83, respectively. The ratio of ke/kh controls electro–osmotically induced negative pore water pressure. The higher the ratio, the higher the pore water pressure difference and the faster the consolidation is. The range of ke/kh was between 5.2 to 9.4 m/V at the void ratios between 0.83 and 0.72, respectively. The ratio of ke/kh increased when void ratio decreased. The high range of ke/kh proved the effectiveness of electro-osmosis consolidation for the Urmia Lake sediments.