Application of Electro-osmosis to Accelerate the Removal of Water form Fine Soils

Document Type : Research Paper

Authors

1 Post graduate of water structures, Irrigation and Reclamation department, college of agricultural and natural resources, University of Tehran.

2 Assistant Prof, Irrigation and Reclamation department, college of agricultural and natural resources, University of Tehran.

3 Ph.D. candidate of water structures, Irrigation and Reclamation department, college of agricultural and natural resources, University of Tehran.

Abstract

Nowadays, application of Electro osmosis to remove water out of the soil is one of the most efficient methods of fine soil improvement. The electric field created by electrodes placed in the soil, cause water molecules move and get extracted from the porous media. In this research, an electro-osmosis system assembled as vertical drains was applied in a laboratory scale, for treatment and improvement of fine soil. For the purpose some saturated clay samples were prepared and placed in the designed physical model and tested. The results showed that using electro osmosis to withdraw water from the soil the quantity of water will be more and the extraction done more quickly. Also an increase in the difference of voltage between cathode and anode will increase the volume of water leaving the soil. Measurement of electrical conductivity (EC) and pH length wise in the soil showed that in electro osmotic process, pH will increase around the cathode and decrease at the anode. while EC being increased at either the cathode or anode. Also it was observed that the applied voltage to the soil sample decreases from anode to the cathode. Then it is concluded that the electro osmotic method can be a suitable alternative for soil settlement instead of surcharge being applied.

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Bjerrum, L., Moum, J., and Eide, O. (1967). Application of electro-osmosis to a foundation problem in a Norwegian Quick Clay. Journal of Ge´otechnique, 17(3), 214–235.
Burnotte, F., Lefebvre, G., and Grondin, G. (2004). A case record of electroosmotic consolidation of clay with improved soil-electrde contact. Canadian Geotechnical Journal, 41: 1038-1053.
Casagrande, L. (1949). Electro-osmosis in soils. Journal of Ge´otechnique, 1(3), 159–177.
Casagrande, L. (1983). Stabilization of soils by means of electro-osmosis: state-of-the-art. Journal of the Boston Society of Civil Engineers Section, ASCE, 69(2), 255–302.
Chew, S. H., Karunaratne, G. P., Kuma, V. M., Lim, L. H., Toh, M. L., and Hee, A. M. (2004). A field trial for soft clay consolidation using electric vertical drains. Journal of Geotextiles and Geomembranes, 22(1), 17–35.
Esrig, M. I. (1968). Pore pressures, consolidation, and electrokinetics. Journal of the Soil Mechanics and Foundations Division, ASCE, 94(4), 899–921.
Fetzer, C. A. (1967). Electro-osmotic stabilization of West Branch Dam. Journal of the Soil Mechanics and Foundations Division, ASCE, 93(4), 122-131.
Lo, K. Y., Ho, K. S., and Inculet I. I. (1991). Field test of electroosmotic strengthening of soft sensitive clay. Canadian Geotechnical Journal, 28(1), 74–83.
Lo, K. Y., Micic, S., Shang, J. Q., Lee, Y. N., and Lee, S. W. (2000). Electrokinetic strengthening of a soft marine sediment. International Journal of Offshore and Polar Engineering, 10 (2), 133–144.
Mitchell, J. K. and Soga, K. (2005) Fundamentals of Soil Behavior. Wiley, New York, 3nd edn.
Mohammed, A. M. O. and Antia, H. E. (1998). Geoenvironmental Engineering. Elsevier, Amsterdam.
Mohamedelhassan, E. and Shang, J. Q. (2001). Effects of electrode materials and current intermittence in electro-osmosis. Ground Improvement, 5(1), 3–11.
Ou, C. Y., Chien, S. C., and Chang, H. H. (2009). Soil improvement using electroosmosis with the injection of chemical solutions: field tests, Canadian Geotechnical Journal, 46: 727- 733.
Rittirong, A. and Shang, J. Q. (2005). Electro-Osmotic stabilization. Elsevier geo-engineering book series.
Rittirong, A., Douglas, R. S., Shang, J. Q., and Lee, E. C. (2008). Electrokinetic improvement of soft clay using electrical vertical drains. Geosynthetics International journal, 15(5), 369–381.
Shang, J. Q. (1997). Zeta potential and electro-osmotic permeability of clay soils. Canadian Geotechnical Journal, 34, 627-631.
Soderman, L. G. and Milligan, L. (1961). Capacity of friction piles in varved clay increased by electro-osmosis. In: Proceeding of the 5th International Conference on Soil and Foundation Engineering, Paris, 2, 143-147.
Wan, T. and Mitchell, J. K. (1976). Electro-osmotic consolidation of soils. Journal of Geotechnical Engineering Division, ASCE, 102(5), 473–491.