Optimization of the Ultimate Bearing Capacity of Reinforced Soft Soils through the Concept of the Critical Length of Stone Columns
The objective of this paper is to develop an analytical equation based on the concept of the critical-length of columns in order to optimize the ultimate bearing-capacity of soft soils, supporting a strip footing and reinforced by a group of floating stone columns. Optimization procedure was performed on three-dimensional numerical models simulated on the Flac3D computer code, for various soft-soils with different undrained-cohesions (Cu=15–35kPa), reinforced by columns of varying lengths (L) and area replacement ratio (As=10-40%), considering different footing widths B. Obtained results indicate that the optimal bearing-capacity ratio (Ultimate bearing-capacity of reinforced soil/unreinforced soil) is reached for the column critical-length ratio (Lc/B) and increase with increase of the later ratio, depending on As and Cu. Analysis of results also showed that the optimal values of the bearing-capacity ratio in the reinforced soils remain bounded between the lower and higher values (1.28-2.32), respectively for minimal and maximal values of the critical-length ratio (1.1) and (4.4). Based on these results, a useful analytical equation is proposed by the authors, for the expression of the critical-length; thus ensuring an optimal pre-dimensioning of the stone columns. The proposed equation was compared with the data available in the literature and showed good agreement.
Full Text: PDF
Barksdale, R. D., & Bachus, R. C. “Design and construction of stone columns,” vol. I (No. FHWA/RD-83/026; SCEGIT-83-104). Turner-Fairbank Highway Research Center (December 1983).
Hanna, A. M., M. Etezad, and T. Ayadat. “Mode of Failure of a Group of Stone Columns in Soft Soil.” International Journal of Geomechanics 13, no. 1 (February 2013): 87–96. doi:10.1061/(asce)gm.1943-5622.0000175.
Hu, W. E. T. “Physical Modelling of Group Behaviour of stone column foundations.” Doctoral dissertation, University of Glasgow (June 1995).
Hughes, J.M.O., and N.J. Withers. “Reinforcing of Soft Cohesive Soils with Stone Columns.” International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 11, no. 11 (November 1974): A234. doi:10.1016/0148-9062(74)90643-3.
Madhav, M. R., and P. P. Vitkar. “Strip Footing on Weak Clay Stabilized with a Granular Trench or Pile.” Canadian Geotechnical Journal 15, no. 4 (November 1, 1978): 605–609. doi:10.1139/t78-066.
Aboshi, H., Ichimoto, E., Enoki, M., and Harada, K. “The composer — a method to improve characteristics of soft clay by inclusion of large diameter sand columns.” In Proceedings of the International Conference on Soil Reinforcement: Reinforced Earth and other Techniques, Paris. Vol. 1. (1979): 211–216.
Muir Wood, D., W. Hu, and D. F. T. Nash. “Group Effects in Stone Column Foundations: Model Tests.” Géotechnique 50, no. 6 (December 2000): 689–698. doi:10.1680/geot.2000.50.6.689.
Balaam, N. P., and J. R. Booker. “Analysis of Rigid Rafts Supported by Granular Piles.” International Journal for Numerical and Analytical Methods in Geomechanics 5, no. 4 (October 1981): 379–403. doi:10.1002/nag.1610050405.
Impe, W. Van. 1983. “Improvement of Settlement Behaviour of Soft Layers by Means of Stone Columns.” In Proceedings, 8th European Conference on Soil Mechanics and Foundation Engineering: Improvement of Ground, 1:309–12.
Jellali, B., M. Bouassida, and P. de Buhan. “A Homogenization Method for Estimating the Bearing Capacity of Soils Reinforced by Columns.” International Journal for Numerical and Analytical Methods in Geomechanics 29, no. 10 (2005): 989–1004. doi:10.1002/nag.441.
Etezad, M., A. M. Hanna, and T. Ayadat. “Bearing Capacity of a Group of Stone Columns in Soft Soil.” International Journal of Geomechanics 15, no. 2 (April 2015): 04014043. doi:10.1061/(asce)gm.1943-5622.0000393.
Mitchell, James K., and Timothy R. Huber. “Performance of a Stone Column Foundation.” Journal of Geotechnical Engineering 111, no. 2 (February 1985): 205–223. doi:10.1061/(asce)0733-9410(1985)111:2(205).
Elshazly, H. A., D. H. Hafez, and M. E. Mossaad. “Reliability of Conventional Settlement Evaluation for Circular Foundations on Stone Columns.” Geotechnical and Geological Engineering 26, no. 3 (January 26, 2008): 323–334. doi:10.1007/s10706-007-9169-9.
Tan, Xin, Longjian Feng, Zhengbo Hu, and Minghua Zhao. “Failure Modes and Ultimate Bearing Capacity of the Isolated Stone Column in Soft Soil.” Bulletin of Engineering Geology and the Environment 80, no. 3 (January 11, 2021): 2629–2642. doi:10.1007/s10064-020-02066-5.
Bouassida, Mounir, Belgacem Jellali, and Ali Porbaha. “Limit Analysis of Rigid Foundations on Floating Columns.” International Journal of Geomechanics 9, no. 3 (May 2009): 89–101. doi:10.1061/(asce)1532-3641(2009)9:3(89).
Salam, Mahmood A., and Qiyao Wang. “Numerical Study on Bearing Capacity and Bulging of the Composite Stone Column.” The Open Civil Engineering Journal 15, no. 1 (March 17, 2021): 13–28. doi:10.2174/1874149502115010013.
Zhou, Haizuo, Yu Diao, Gang Zheng, Jie Han, and Rui Jia. “Failure Modes and Bearing Capacity of Strip Footings on Soft Ground Reinforced by Floating Stone Columns.” Acta Geotechnica 12, no. 5 (April 4, 2017): 1089–1103. doi:10.1007/s11440-017-0535-3.
Lee, J. S., and G. N. Pande. "Analysis of stone‐column reinforced foundations." International Journal for Numerical and Analytical Methods in Geomechanics 22, no. 12 (1998): 1001-1020. doi:10.1002/(SICI)1096-9853(199812)22:12<1001::AID-NAG955>3.0.CO;2-I.
Kumar, G., and M. Samanta. “Experimental Evaluation of Stress Concentration Ratio of Soft Soil Reinforced with Stone Column.” Innovative Infrastructure Solutions 5, no. 1 (February 12, 2020). doi:10.1007/s41062-020-0264-6.
Thakur, Ankit, Saurabh Rawat, and Ashok Kumar Gupta. “Experimental and Numerical Investigation of Load Carrying Capacity of Vertically and Horizontally Reinforced Floating Stone Column Group.” Geotechnical and Geological Engineering 39, no. 4 (January 2, 2021): 3003–3018. doi:10.1007/s10706-020-01674-y.
Bora, Mukul. “Regression Model for Floating Stone Column Improved Soft,” Proceedings of Indian Geotechnical Conference IGC-2014 no (December 2014).
Fattah, Mohammed Y., Mohammed A. Al-Neami, and Ahmed Shamel Al-Suhaily. “Estimation of Bearing Capacity of Floating Group of Stone Columns.” Engineering Science and Technology, an International Journal 20, no. 3 (June 2017): 1166–1172. doi:10.1016/j.jestch.2017.03.005.
Najjar, Shadi S., Salah Sadek, and Tarek Maakaroun. “Effect of Sand Columns on the Undrained Load Response of Soft Clays.” Journal of Geotechnical and Geoenvironmental Engineering 136, no. 9 (September 2010): 1263–1277. doi:10.1061/(asce)gt.1943-5606.0000328.
McKelvey, D., V. Sivakumar, A. Bell, and J. Graham. “Modelling Vibrated Stone Columns in Soft Clay.” Geotechnical Engineering 157, no. 3 (July 2004): 137–149. doi:10.1680/geng.126.96.36.199416.
Black, J. A., V. Sivakumar, M. R. Madhav, and G. A. Hamill. “Reinforced Stone Columns in Weak Deposits: Laboratory Model Study.” Journal of Geotechnical and Geoenvironmental Engineering 133, no. 9 (September 2007): 1154–1161. doi:10.1061/(asce)1090-0241(2007)133:9(1154).
Das, Braja M. "Bearing capacity of shallow foundation on granular column in weak clay." In Foundation Engineering: Current Principles and Practices, ASCE (1989): 1252-1263.
Castro, Jorge. “Numerical Modelling of Stone Columns Beneath a Rigid Footing.” Computers and Geotechnics 60 (July 2014): 77–87. doi:10.1016/j.compgeo.2014.03.016.
FLAC3D, Itasca. “Fast Lagrangian Analysis of Continua in 3 D.” Itasca Consulting Group, Ver. 3.10. Inc., (2006).
Ambily, A. P., and Shailesh R. Gandhi. “Behavior of Stone Columns Based on Experimental and FEM Analysis.” Journal of Geotechnical and Geoenvironmental Engineering 133, no. 4 (April 2007): 405–415. doi:10.1061/(asce)1090-0241(2007)133:4(405).
Khalifa, M., M. Etezad, A. Hanna, and M. Sabry. “Bearing Capacity of Strip Foundation on Soft Soil Reinforced with Stone Columns Using Method of Slices.” Sustainable Civil Infrastructures (July 12, 2017): 79–91. doi:10.1007/978-3-319-61902-6_8.
Das, Manita, and Ashim Kanti Dey. “State of Art on Load-Carrying Capacity and Settlements of Stone Columns.” Lecture Notes in Civil Engineering (July 3, 2020): 101–124. doi:10.1007/978-981-15-4577-1_9.
Ladd, Charles C. “Stress-Strain Modulus of Clay in Undrained Shear.” Journal of the Soil Mechanics and Foundations Division 90, no. 5 (September 1964): 103–132. doi:10.1061/jsfeaq.0000647.
Dheerendra Babu, M. R., Sitaram Nayak, and R. Shivashankar. “A Critical Review of Construction, Analysis and Behaviour of Stone Columns.” Geotechnical and Geological Engineering 31, no. 1 (September 13, 2012): 1–22. doi:10.1007/s10706-012-9555-9.
Etezad, M., A. M. Hanna, and M. Khalifa. “Bearing Capacity of a Group of Stone Columns in Soft Soil Subjected to Local or Punching Shear Failures.” International Journal of Geomechanics 18, no. 12 (December 2018): 04018169. doi:10.1061/(asce)gm.1943-5622.0001300.
Zhang, Zhen, Jie Han, and Guanbao Ye. “Numerical Investigation on Factors for Deep-Seated Slope Stability of Stone Column-Supported Embankments over Soft Clay.” Engineering Geology 168 (January 2014): 104–113. doi:10.1016/j.enggeo.2013.11.004.
- There are currently no refbacks.
Copyright (c) 2021 Nour el islam Boumekik, Mohamed Labed, Mekki Mellas, Abdelhak Mabrouki
This work is licensed under a Creative Commons Attribution 4.0 International License.