Enhancement in Effectiveness of Cemented Stone Columns for Soft Clay Ground Improvement by Providing Underreamed Bulbs
Publication: International Journal of Geomechanics
Volume 18, Issue 11
Abstract
A straight-shafted cemented stone column technique for effective improvement of soft clay ground was reported in 2017. The method involved transforming the conventionally used uncemented stone or granular mix fill material from a bulging type to a cemented porous fill material of a semirigid nonbulging type. This paper addresses further improvement in the performance of cemented stone columns by incorporating an underreamed enlarged bulb in the column at its bottom or at a suitable intermediate level. Analytical and experimental studies were conducted on such underreamed cemented stone columns in soft clay. Considering an idealized load-transfer mechanism and failure mode, expressions were then developed for predicting the load-carrying capacity of soft clay ground treated with underreamed cemented stone columns. Two cases were considered in the present study: one for an enlarged bulb at the bottom of the stone column and another with a bulb at an intermediate level (at a depth of 5 times the column diameter). The laboratory investigations involved load tests of six unit cells of bulbed cemented stone columns in soft clayey soil, corresponding to area replacement ratios of 4% and 9% and column length ratios of 10, 11.67, and 13.33. The measured values of load-carrying capacity agreed very closely with theoretically computed values. Additionally, straight-shafted conventional uncemented stone columns with four other unit cells were also load tested. The test data of these 10 unit cells in the present study along with the six-unit-cell test data reported earlier were combined and analyzed to evaluate the performance of underreamed cemented stone columns in comparison to other systems of stone columns in soft clays. It was found that the cemented stone columns with an underreamed enlarged bulb at the bottom or at a depth 5 times the shaft diameter were highly effective in improving the soft clay ground condition with respect to both the load-carrying capacity and ground stiffness. The provision of a bulb at the intermediate level was found to be better than a bulb at the bottom of the cemented stone columns.
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Acknowledgments
The assistance provided by V. Satyanarayana and Ch. S. S. V. Raju in the tedious and complex laboratory investigation involving soft plastic clay is highly acknowledged. They worked hard to attain the highest possible perfection during various stages of the investigation. Comments and suggestions from peer reviewers also enabled us to enhance the technical quality of the original paper.
References
Alamgir, M., N. Miura, H. B. Poorooshasb, and M. R. Madhav. 1996. “Deformation analysis of soft ground reinforced by columnar inclusions.” Comput. Geotech. 18 (4): 267–290. https://doi.org/10.1016/0266-352X(95)00034-8.
Al-Saoudi, N. K. S., F. Rahil, and Z. Abbawi. 2015. “Soft soil improved by stone columns and/or ballast layer.” Ground Improv. 168 (3): 179–186. https://doi.org/10.1680/grim.12.00035.
Babu, M. R. D., R. Shivshankar, S. S. Nayak, and J. A. Majid. 2010. “Load settlement behavior of stone column with circumferential nails.” In Vol. 2 of Proc., Indian Geotechnical Conf. 2010, edited by B. V. S. Vishwanadham and D. Choudhury, 579–582. New Delhi, India: Macmillan.
Barksdale, R. D., and R. C. Bachus. December 1983. Design and construction of stone columns. FHWA Rep. No. RD. 83/026, Vol. 1. Washington, DC: Federal Highway Administration.
BIS (Bureau of Indian Standards). 1970. Classification and identification of soils for general engineering purposes. BIS-1498. New Delhi, India: BIS.
BIS (Bureau of Indian Standards). 1980. Code of practice for design and construction of under-reamed piles. BIS-1498. New Delhi, India: BIS.
Castro, J. 2014. “Numerical modelling of stone columns beneath a rigid footing.” Comput. Geotech. 60: 77–87. https://doi.org/10.1016/j.compgeo.2014.03.016.
Castro, J., M. Karstunen, and N. Sivasithamparam. 2014. “Influence of stone column installation on settlement reduction.” Comput. Geotech. 59: 87–97. https://doi.org/10.1016/j.compgeo.2014.03.003.
Chen, J. F., L. Y. Li, J. F. Xue, and S. Z. Feng. 2015. “Failure mechanism of geosynthetic-encased stone columns in soft soils under embankment.” Geotext. Geomembr. 43 (5): 424–431. https://doi.org/10.1016/j.geotexmem.2015.04.016.
Das, A. K., and K. Deb. 2014. “Modeling of uniformly loaded circular raft resting on stone column-improved ground.” Soils Found. 54 (6): 1212–1224. https://doi.org/10.1016/j.sandf.2014.11.014.
Datey, K. R., and S. S. Nagaraju. 1977. “Installation and testing of rammed stone columns.” In Vol. 1 of Proc., IGS Special Session, 5th Asian Regional Conf. on Soil Mechanics and Foundation Engineering, 101–104. Bangalore, India: IGS.
Deb, K. 2010. “A mathematical model to study the soil arching effect in stone column-supported embankment resting on soft foundation soil.” Appl. Math. Modell. 34 (12): 3871–3883. https://doi.org/10.1016/j.apm.2010.03.026.
Deb, K., P. K. Basudhar, and S. Chandra. 2010. “Extensible geosynthetics and stone-column-reinforced soil.” Ground Improv. 163 (4): 231–236. https://doi.org/10.1680/grim.2010.163.4.231.
Deb, K., N. K. Samadhiya, and B. N. Jagtap. 2011. “Laboratory model studies on unreinforced and geogrid-reinforced sand bed over stone column-improved soft clay.” Geotext. Geomembr. 29 (2): 190–196. https://doi.org/10.1016/j.geotexmem.2010.06.004.
Dutta, S., M. B. Nadaf, B. Ram Rathan Lal, and J. N. Mandal. 2016. “Encased stone columns for soft ground improvement.” In Proc., Sustainability, Energy, and the Geoenvironment, Geo-Chicago—2016, 746–755. Chicago: ASCE.
Dutta, S., A. H. Padade, and J. N. Mandal. 2012. “Experimental study on natural bamboo geogrid encased stone column.” In Proc., 5th Asian Regional Conf. on Geosynthetics, Geosynthetics Asia 2012, 417–426. Bangkok, Thailand: International Geosynthetics Society (IGS).
Farouk, A., and M. M. Shahien. 2013. “Ground improvement using soil–cement columns: Experimental investigation.” Alexandria Eng. J. 52 (4): 733–740. https://doi.org/10.1016/j.aej.2013.08.009.
Fattah, M. Y., K. T. Shlash, and M. J. Al-Waily. 2013. “Experimental evaluation of stress concentration ratio of model stone columns strengthened by additives.” Int. J. Phys. Modell. Geotech. 13 (3): 79–9. https://doi.org/10.1680/ijpmg.12.00006.
Gniel, J., and A. Bouazza. 2009. “Improvement of soft soil using geogrid encased stone column.” Geotext. Geomembr. 27 (3): 167–175. https://doi.org/10.1016/j.geotexmem.2008.11.001.
Golait, Y. S., and A. H. Padade. 2017. “Analytical and experimental studies on cemented stone columns for soft clay ground improvement.” Int. J. Geomech. 17 (4): 04016100. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000779.
Gueguin, M., G. Hassen, and P. deBuhan. 2015. “Stability analysis of homogenized stone column reinforced foundations using a numerical yield design approach.” Comput. Geotech. 64: 10–19. https://doi.org/10.1016/j.compgeo.2014.11.001.
Han, J., and S. L. Ye. 2002. “A theoretical solution for consolidation rate of stone column-reinforced foundations accounting for smear and wall resistance effect.” Int. J. Geomech. 2 (2): 135–151. https://doi.org/10.1061/(ASCE)1532-3641(2002)2:2(135).
Hanna, A., M. Etezad, and T. Ayadat. 2013. “Mode of failure of a group of stone columns in soft soil.” Int. J. Geomech. 13 (1): 87–96. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000175.
Hassen, G., M. Gueguin, and P. deBuhan. 2013. “A homogenization approach for assessing the yield strength properties of stone column reinforced soils.” Eur. J. Mech. 37: 266–280. https://doi.org/10.1016/j.euromechsol.2012.07.003.
Hughes, J. M. O., and N. J. Withers. 1974. “Reinforcing of soft cohesive soils with stone columns.” Ground Eng. 7 (3): 42–49.
Killeen, M. M., and B. A. McCabe. 2014. “Settlement performance of pad footings on soft clay supported by stone columns: A numerical study.” Soils Found. 54 (4): 760–776. https://doi.org/10.1016/j.sandf.2014.06.011.
Madhav, M. R. 1983. “Recent developments in the use and analysis of granular piles.” In Proc., Int. Symp. on Recent Developments in Ground Improvement Techniques, 117–129. Bangkok, Thailand.
Maher, M. H., and D. H. Gray. 1990. “Static response of sand reinforced with randomly distributed fibres.” J. Geotech. Eng. Div. 116 (11): 1661–1677. https://doi.org/10.1061/(ASCE)0733-9410(1990)116:11(1661).
Mayerhof, G. G. 1951. “The ultimate bearing capacity of foundations.” Geotechnique 2 (4): 301–331. https://doi.org/10.1680/geot.1951.2.4.301.
Mitchell, J., and T. Huber. 1985. “Performance of a stone column foundation.” J. Geotech. Eng. 111 (2): 205–223. https://doi.org/10.1061/(ASCE)0733-9410(1985)111:2(205).
Murugesan, S., and K. Rajagopal. 2006. “Geosynthetic-encased stone columns: Numerical evaluation.” Geotex. Geomembr. 24 (6): 349–358. https://doi.org/10.1016/j.geotexmem.2006.05.001.
Nayak, S., R. Shivashankar, and M. R. D. Babu. 2011. “Performance of stone columns with circumferential nails.” Ground Improv. 164 (2): 97–106. https://doi.org/10.1680/grim.2011.164.2.97.
Prandtl, L. 1920. “Uber die Harte Plastischer Korper.” In Nachrichten vander Koniglichen Gesellschaft der Wissenschaften zu Gottingen, 74–85. Berlin.
Raithel, M., H. G. Kempfert, and A. Kirchner. 2002. “Geotextile-encased columns for foundation as a dike on very soft soils.” In Proc., 7th Int. Conf. on Geosynthetics. Nice, France.
Ranjan, G., and B. G. Rao. 1983. “Skirted granular piles for ground improvement.” In Proc., 8th European Conf. on Soil Mechanics and Foundation Engineering. Helsinki, Finland.
Rao, N. B. S., and I. G. Nayak. 1995. “Model studies on partially confined sand columns using geogrid tubes.” Indian Geotech. J. 25 (3): 365–378.
Samadhiya, N. K., P. Maheshwari, P. Basu, and M. B. Kumar. 2008. “Load settlement characteristics of granular piles with randomly mixed fibres.” In Vol. 3 of Proc., Indian Geotechnical Conf. 2008, 345–354. Madras, India: IGS.
Shahu, J., and Y. Reddy. 2011. “Clayey soil reinforced with stone column group: Model tests and analyses.” J. Geotech. Geoenviron. Eng. 137 (12): 1265–1274. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000552.
Skempton, A. W. 1951. The bearing capacity of clays. London: Building Research Congress, Institute of Civil Engineers, Div-I.
Terzaghi, K. 1943. Theoretical soil mechanics, 118–143. New York: John Wiley & Sons.
Yoo, C. 2010. “Performance of geosynthetic-encased stone columns in embankment construction: Numerical investigation.” J. Geotech. Geoenviron. Eng. 136 (8): 1148–1160. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000316.
Yoo, C. 2015. “Settlement behavior of embankment on geosynthetic-encased stone column installed soft ground—A numerical investigation.” Geotext. Geomembr. 43 (6): 484–492. https://doi.org/10.1016/j.geotexmem.2015.07.014.
Zhang, L., and M. Zhao. 2014. “Deformation analysis of geotextile-encased stone columns.” Int. J. Geomech. 15 (3): 04014053. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000389.
Zhang, L., M. Zhao, C. Shi, and H. Zhao. 2013. “Settlement calculation of composite foundation reinforced with stone columns.” Int. J. Geomech. 13 (3): 248–256. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000212.
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Published In
International Journal of Geomechanics
Volume 18 • Issue 11 • November 2018
Copyright
© 2018 American Society of Civil Engineers.
History
Received: Oct 25, 2017
Accepted: May 3, 2018
Published online: Aug 31, 2018
Published in print: Nov 1, 2018
Discussion open until: Jan 31, 2019
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