Experimental Investigation on the Effect of Geometry and Reinforced Floating Stone Columns on Bearing Capacity

Document Type : پژوهشی

Authors

• Nima Mehrannia ¹
• javad nazariafshar ²
• Farzin Kalantary ³

¹ islamic azad university science and research branch

² islamic azad university share-ghods branch

³ K.N. Toosi University of Technology

10.22067/civil.v31i2.57449

Abstract

Using stone column is an efficient method to increase bearing capacity of soft soils. In this research, the bearing capacity of flouting stone columns in reinforced and unreinforced modes were examined using large-scale laboratory tests. The stone columns used in this study are with 60mm diameter with 200 and 350mm length and 80mm diameter with 400mm length. These columns are reinforced with nonwoven geotextile. Results show that increasing in diameter and length of stone column and using geotextile as encased stone column increased bearing capacity of stone column. Increasing the diameter of stone column is more effective than increasing the length of stone column. In fact, it is better to use stone column with excessive diameter and proper length (length to diameter ratio more than 5) instead of excessive length and fewer diameters. By using geotextile encasement, stress concentration ratio increased and so bearing capacity improved. Encasing stone column with excessive diameter is more effective than excessive length.

Keywords

• Stone Column
• Bearing Capacity
• Geotextile, Reinforcing
• Ground Improvement

---

References

1. Greenwood, D.A., "Mechanical improvement of soils below ground surface", In: Proceedings of Ground Improvement Conference. Institute of Civil Engineering, pp. 9-29, (1970).

2. Hughes JMO, Withers NJ, "Reinforcing of soft cohesivesoils with stone columns", Ground Engineering, Vol. 7(3), pp. 42–49, (1974).

3. McKenna JM, Eyre WA., and Wolstenholme DR, "Performance of anembankment supported by stone columns in soft ground", Geotechnique, Vol. 25(1), pp. 51-59, (1975).

4. Barksdale, R.D., Bachus, R.C., "Design and construction of stone column", Report No.FHWA/RD-83/026. National Technical Information Service, Springfield, Virginia, (1983).

5. Gniel, J. and Bouazza, A., "Improvement of soft soils using geogrid encased stone columns", Geotextiles and Geomembranes, Vol. 27 (3), pp.167-175, (2008).

6. Ghazavi, M. and Nazari Afshar, J., "Bearing capacity of geosynthetic encased stone columns", Geotextiles and Geomembranes Journal, pp.1-11, (2013).

7. FGSV (Fors chungs gesellschaft f. Straßen- und Verkehrswesen) "Merkblatt für die Unter grund verbesse rung durch Tiefenrüttler", FGSV, Köln, (1979).

8. Raju, V. R, "The Behaviour of Very Soft Soils Improved by Vibro Replacement", Ground Improvement Conference, London, (1997).

9. Van Impe, W. F., "Soil improvement techniques and their evolution", Balkema,Rotterdam, The Netherlands, (1989).

10. Christoulas, S.T., Bouckovalas, G. and Giannaros, C. H., "An experimental studyon model stone columns", Soils and Foundations Journal, Vol. 40(6), pp. 11-22, (2000).

11. Malarvizhi, S. N., and Ilamparuthi, K., "Load versus settlement of clay-bed stabilized with stone and reinforced stone columns", Proceeding of the 3rd Asian Regional Conference on Geosynthetics, GEOASIA, Seoul, Korea, pp. 322-329, )2004(.

12. Murugesan, S., and Rajagopal, K., "Geosynthetic-encased stone columns: numerical evaluation", Geotextiles and Geomembranes Journal, 24(6), pp. 349-358, )2006(.

13. Nazari Afshar, J. Ghazavi, M. "Experimental studies on bearing capacity of geosynthetic reinforced stone columns", Arabian Journal for Science and Engineering(AJSE), DOI 10,1007/s13369-013-0709-8, (2013).

14. Nazari Afshar, J. Ghazavi, M. "A Simple analytical method for calculation of bearing capacity of stone-column", International Journal of Civil Engineering, Vol. 12(1) Transaction B: Geotechnical Engineering, (2014).

15. Selig, E.T., McKee, K.E., "Static and dynamic behavior of small footings", Journal of Soil Mechanics and Foundation. Div. ASCE, Vol. 87 (6), pp. 29-47, (1961).

16. Chummer, A.V., "Bearing capacity theory from experimental results". J. Soil Mech. Found. Div. ASCE 98 (12), pp.1311-1324, (1972).

17. Iai, S., "Similitude for shaking table tests on soil-structure fluid models in 1ggravitational field. Soils and Foundations", 29 (1), pp.105-118, (1989).

18. Dash, SK., Bora, MC., "Improved performance of soft clay foundations using stone columnsand geocell-sand mattress", Geotextiles and Geomembranes Journal, 41, pp. 26-35, (2013).

19. Hong, Y.S., Wu, C.S, Yu, Y.S., "Model tests on geotextile-encased granular columns under 1-g and undrained conditions", Geotextiles and Geomembranes Journal 44, pp. 13-27, (2016).

20. Ali, K., Shahu, J.T., Sharma, K.G., "Behavior of reinforced stone columns in soft soils", Indian Geotechnical Conference, GEOtrend, IGS Mumbai Chapter & IIT Bombay, (2010).

21. Fattah, M. Y., Shlash, K. T., Al-Waily, M. J. M., "Stress concentration ratio of model stone columns in soft clays", Geotechnical Testing Journal, Vol. 34, No. 1, Paper ID GTJ103060, ASTM, Nov. 29 14:27:16 EST, (2010).

22. Murugesan, S. and Rajagopal, K., "Studies on the behavior of single and group of geosynthetic encased stone columns", Journal of Geotechnical And Geo Environmental Engineering, ASCE, Vol. 136(1), pp. 129-139, (2010).