Soil Improvement by Electrokinetic Injection

Document Type : Research Article

Authors

Abstract

In this study, a non-plastic silt is grouted by sodium silicate in an electrokinetic cell. The silicate solutions are injected through the reservoir next to the anode electrode. The injection of Na- silicate solution increases the strength adjacent to the anode electrode between 5 to 8 times compared with the base soil. Increasing silicate concentration generates lower increase in strength across the specimen. This means that decreasing the silicate concentration increases the penetration length of the grout. Neglecting the results for anode side of the specimens, the maximum increase in strength has been observed for injection of 5% silicate solution through the anode with acid in the cathode chamber. The obtained strength is 3.3 to 4.0 times greater than the strength of the base soil with the highest penetration length. The application of this technology for increasing the strength of the soil underneath an existing foundation or generation of   pile through the soil is proven.

Keywords


[1]Karol, R. H.; Chemical Grouting, 2 nd ed., Marcel Dekker, Inc., New York, NY, 1990._
[2]Mitchell, J. K.; “Soil Improvement- State- of- the- Art,” Proc. 10th ICSFME, Stockholm, Vol. 4, 509-565, 1981,_
[3]Tolstopjatow, K; “woprou ob elektrochimitscheskom ukreplenii gruntow”,Potschwowedenie 8. Tondorf, S., Grundlagen der
Elektrosanierung, TerraTech 4, 66–69, 1940._
[4]Youell, R. F., “An Electrolytic Method for Producing Chlorite-Like Substances from Montmorillonite”, Clay Miner. Bull. 9, 191-195,
1959._
[5]Holmes, W. J., “Electroosmosis and civil engineer. Civ. Eng.” Public Works Rev., 58(682): 624-626, 1963._
[6]Gray, D. H., “Electrochemical Hardening of Clay Soils”, Geotechnique, Vol. 20, No.1, pp. 81-93,1970.
[7]O’Bannon, D. E.r, Morris, G. R., and Mancini, F. P., “Electrochemical hardening of expansive clays.” Transp. Res. Rec. 593, Transportation Research Board, Washington, D.C., 46–50, 1976.
[8]Feldkamp, J R. and Belhomme, G. M., “Large- strain electrokinetic consolidation: theory and experiment in one dimension”, Geotechnique 40,No. 4, 557-568, 1990.
[9]Ozkan, S., Gale, R.J., and Seals, R.K., “Electrokinetic Stabilization of Kaolinite by Injection of Al and PO43- Ions”, Ground
Improvement, 3(4): 135-144, 1999.
[10]Mohamedelhassan, E., and Shang, J.Q., “Electrokinetics-Generated Pore Fluid And Ionic Transport In An Offshore Calcareous Soil”, Can. J.Geotech. /Rev. Can. Geotech. 40(6): 1185-1199,2003.
[11]Shang, J.Q., E. Mohamedelhassan, and M. Ismail, “Electrochemical cementation of offshore calcareous soil”. Can. Geotech. J. 41: 877–893,2004.
[12]Alshawabkeh, A. N. and Sheahan, T., “Soft soil stabilisation by ionic injection under electric fields”, Ground Improvement, Pub: Thomas Telford, Vol 7, Issue: 4, pp 177-185. 2004.
[13]Thevanayagam, S. and Jia, W., “Electro-Osmotic Grouting for Liquefaction Mitigation in Silty Soils”, ASCE Special Technical Publication., Grouting, Louisiana, Feb. 2003.
[14]Alshawabkeh, A. N., Yeung, A. and Bricka, R. M, “Practical aspects of in situ electrokinetic remediation,” ASCE Journal of Environmental Engineering, accepted, in press. 1999.
[15]Acar, Y. B. and Alshawabkeh, A. N. “Principles of Electrokinetic Remediation,” Environmental Science and Technology, 27(13): 2638-2647, 1993.
[16]Tani, K., and Craig, W.H., “Bearing capacity of circular foundations on soft clay of strength increasing with depth”. Soils and Foundations,35(4): 21–35, 1995.
[17]Segall, B. A., O’Bannon, C. E., Matthias, J. A., “Electro-Osmosis Chemistry and Water Quality,” ASCE, Journal of Geotechnical Engineering, Vol.106, No. GT10, pp. 1148-1152, 1980.
[18]Alshawabkeh, A.N., Sheahan, T., “Stabilizing fine- grained soils by phosphate electro-grouting”,Journal of the Transportation Research Board (1787), 53–60, 2002.