Numerical Modeling of Encased Stone Columns Supporting Embankments on Sabkha Soil

Imad Eddine Debbabi, Remadna Mohamed Saddek, Ahmad Safuan A. Rashid, Abubakar Sadiq Muhammed


The present research work is concerned with the construction of road embankments on a specific soil called Sabkha in Algeria. This soil is not only soft and very humid during the flooding seasons but also has frequent small areas of very soft soil which we here call Locally Weak Zones (LWZ). LWZ is characterized by low strength and high compressibility. The paper presents the results of two-dimensional axisymmetric numerical analyze that were carried out using PLAXIS 2D 2017, for the modeling of an embankment supported by stone columns on Sabkha soil. The study focuses on the evaluation of the maximum bulging of the stone column and on the settlement of the embankment. It has been demonstrated that Ordinary Stone Columns (OSC) were ineffective due to excessive bulging (221.16 mm) caused by the lack of lateral pressure. On the other hand, the Encased Stone Columns (ESC) showed good behavior, namely a much reduced bulging (42.09 mm) and a reasonable settlement (0.962 m vs. 1.560 m for an OSC) so that it is possible to build safe very high embankments. The numerical analysis also shows that the length of the encasement should just be greater than the depth of the LWZ. Besides, an extensive parametric study was conducted to investigate the effects of the variations of embankment height, stiffness of geosynthetic, the depth of the locally weak zone, area replacement ratio (ARR), and the stone column friction angle, on the performance of the (ESC) - embankment composite in (LWZ). Some important guidelines for selecting the ideal encased stone column (ESC) to support embankments on over locally weak zone were established through this numerical study.


Encased Stone Columns; Geosynthetic; Finite Element Modelling; Locally Weak Zone; Sabkha Soil.


Greenwood, D. (1970). “Mechanical improvement of soils below ground surface.” Paper presented at the Inst Civil Engineers Proc, London/UK/.

Barksdale, Richard D., and Robert Charles Bachus. “Design and construction of stone columns,” vol. I. No. FHWA/RD-83/026; SCEGIT-83-104. Turner-Fairbank Highway Research Center, (1983).

Karkush, Mahdi O, and Anwar Jabbar. “Improvement of Soft Soil Using Linear Distributed Floating Stone Columns Under Foundation Subjected to Static and Cyclic Loading.” Civil Engineering Journal 5, no. 3 (March 19, 2019): 702. doi:10.28991/cej-2019-03091280.

Mohtasham, Mohammad Reza, and Mahdi Khodaparast. “Investigation of the Effect of Dimensional Characteristics of Stone Column on Load-Bearing Capacity and Consolidation Time.” Civil Engineering Journal 4, no. 6 (July 4, 2018): 1437. doi:10.28991/cej-0309184.

Murugesan, S., and K. Rajagopal. “Model Tests on Geosynthetic-Encased Stone Columns.” Geosynthetics International 14, no. 6 (December 2007): 346–354. doi:10.1680/gein.2007.14.6.346.

Abusharar, Sari W., and Jie Han. “Two-Dimensional Deep-Seated Slope Stability Analysis of Embankments over Stone Column-Improved Soft Clay.” Engineering Geology 120, no. 1–4 (June 2011): 103–110. doi:10.1016/j.enggeo.2011.04.002.

Choobbasti, A. J., A. Zahmatkesh, and R. Noorzad. “Performance of Stone Columns in Soft Clay: Numerical Evaluation.” Geotechnical and Geological Engineering 29, no. 5 (May 18, 2011): 675–684. doi:10.1007/s10706-011-9409-x.

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.

Brauns, J. “Die anfangstraglast von schottersäulen im bindigen untergrund.” (1978).

Aboshi, H. “The" Compozer"-a method to improve characteristics of soft clays by inclusion of large diameter sand columns.”. Paris. (1979).

A Rashid, Ahmad Safuan, Aliff Ridzuan Bunawan, and Khairun Nissa Mat Said. “The Deep Mixing Method: Bearing Capacity Studies.” Geotechnical and Geological Engineering 35, no. 4 (March 10, 2017): 1271–1298. doi:10.1007/s10706-017-0196-x.

Sharma, Radhey S, BR Phani Kumar, and G Nagendra. “Compressive Load Response of Granular Piles Reinforced with Geogrids.” Canadian Geotechnical Journal 41, no. 1 (February 1, 2004): 187–192. doi:10.1139/t03-075.

Hasan, Murtaza, and N. K. Samadhiya. “Soft Soils Improvement by Granular Piles Reinforced with Horizontal Geogrid Strips.” International Journal of Geotechnical Engineering 12, no. 1 (November 17, 2016): 101–108. doi:10.1080/19386362.2016.1252139.

Rao, B., and Bhandari, R. “Skirting—a new concept in design of heavy storage tank foundation.” Paper presented at the Proceedings of the 6th South-East Conference on soil Engineering, Taipei, Taiwan. (1980).

Juran, I., and Riccobono, O. “Reinforcing soft soils with artificially cemented compacted-sand columns.” Journal of Geotechnical Engineering 117, no. 7 (July 1991): 1042–1060. doi:10.1061/(ASCE)0733-9410(1991)117:7(1042).

Van Impe, W., and Silence, P. “Improving of the bearing capacity of weak hydraulic fills by means of geotextiles.” International conference on geotextiles (1986): 1411-1416.

Raithel, M., H. G. Kempfert, and A. Kirchner. "Geotextile-encased columns (GEC) for foundation of a dike on very soft soils." In Proc., 7th Int. Conf. on Geosynthetics, vol. 3, Balkema, Rotterdam, Netherlands: GIGSA, (2002): 1025-1028.

Montez, F., and Brasil, H. “First Use Of Geosynthetic Encased Sand Columns In South America.”.

Malarvizhi, S. N., and K. Ilamparuthi. "Load versus settlement of clay bed stabilized with stone and reinforced stone columns." In 3rd Asian Regional Conference on Geosynthetics, (2004): 322-329.

Ayadat, T., and A. M. Hanna. “Encapsulated Stone Columns as a Soil Improvement Technique for Collapsible Soil.” Proceedings of the Institution of Civil Engineers - Ground Improvement 9, no. 4 (October 2005): 137–147. doi:10.1680/grim.2005.9.4.137.

Murugesan, S., and K. Rajagopal. “Studies on the Behavior of Single and Group of Geosynthetic Encased Stone Columns.” Journal of Geotechnical and Geoenvironmental Engineering 136, no. 1 (January 2010): 129–139. doi:10.1061/(asce)gt.1943-5606.0000187.

Raithel, Marc, and Hans-Georg Kempfert. "Calculation models for dam foundations with geotextile coated sand columns." In ISRM International Symposium. International Society for Rock Mechanics and Rock Engineering, (November 2000): 19–24.

Castro, Jorge, and César Sagaseta. “Deformation and Consolidation Around Encased Stone Columns.” Geotextiles and Geomembranes 29, no. 3 (June 2011): 268–276. doi:10.1016/j.geotexmem.2010.12.001.

Pulko, Boštjan, Bojan Majes, and Janko Logar. “Geosynthetic-Encased Stone Columns: Analytical Calculation Model.” Geotextiles and Geomembranes 29, no. 1 (February 2011): 29–39. doi:10.1016/j.geotexmem.2010.06.005.

Zhang, Yiping, Tao Li, and Yang Wang. “Theoretical Elastic Solutions for Foundations Improved by Geosynthetic-Encased Columns.” Geosynthetics International 18, no. 1 (February 2011): 12–20. doi:10.1680/gein.2011.18.1.12.

Zhou, Yang, and Gangqiang Kong. “Deformation Analysis of Geosynthetic-Encased Stone Column–Supported Embankment Considering Radial Bulging.” International Journal of Geomechanics 19, no. 6 (June 2019): 04019057. doi:10.1061/(asce)gm.1943-5622.0001426.

Duan, Yuan-yu, Yi-ping Zhang, Dave Chan, and Ya-nan Yu. “Theoretical Elastoplastic Analysis for Foundations with Geosynthetic-Encased Columns.” Journal of Zhejiang University SCIENCE A 13, no. 7 (July 2012): 506–518. doi:10.1631/jzus.a1100334.

Araujo, G.L.S., E.M. Palmeira, and R.P. Cunha. “Behaviour of Geosynthetic-Encased Granular Columns in Porous Collapsible Soil.” Geosynthetics International 16, no. 6 (December 2009): 433–451. doi:10.1680/gein.2009.16.6.433.

Kaliakin, Victor N., Majid Khabbazian, and Christopher L. Meehan. “Modeling the Behavior of Geosynthetic Encased Columns: Influence of Granular Soil Constitutive Model.” International Journal of Geomechanics 12, no. 4 (August 2012): 357–369. doi:10.1061/(asce)gm.1943-5622.0000084.

Keykhosropur, L., A. Soroush, and R. Imam. “3D Numerical Analyses of Geosynthetic Encased Stone Columns.” Geotextiles and Geomembranes 35 (December 2012): 61–68. doi:10.1016/j.geotexmem.2012.07.005.

Murugesan, S, and K Rajagopal. “Geosynthetic-Encased Stone Columns: Numerical Evaluation.” Geotextiles and Geomembranes 24, no. 6 (December 2006): 349–358. doi:10.1016/j.geotexmem.2006.05.001.

Yoo, C., and S.-B. Kim. “Numerical Modeling of Geosynthetic-Encased Stone Column-Reinforced Ground.” Geosynthetics International 16, no. 3 (June 2009): 116–126. doi:10.1680/gein.2009.16.3.116.

Akili, W., and J. K. Torrance. “The Development and Geotechnical Problems of Sabkha, with Preliminary Experiments on the Static Penetration Resistance of Cemented Sands.” Quarterly Journal of Engineering Geology and Hydrogeology 14, no. 1 (February 1981): 59–73. doi:10.1144/gsl.qjeg.1981.014.01.05.

Abduljauwad, S.N., and O.S.B. Al-Amoudi. “Geotechnical Behaviour of Saline Sabkha Soils.” Géotechnique 45, no. 3 (September 1995): 425–445. doi:10.1680/geot.1995.45.3.425.

Zhang, Ling, and Minghua Zhao. “Deformation Analysis of Geotextile-Encased Stone Columns.” International Journal of Geomechanics 15, no. 3 (June 2015): 04014053. doi:10.1061/(asce)gm.1943-5622.0000389.

Benmebarek, Sadok, Fouad Berrabah, and Naïma Benmebarek. “Effect of Geosynthetic Reinforced Embankment on Locally Weak Zones by Numerical Approach.” Computers and Geotechnics 65 (April 2015): 115–125. doi:10.1016/j.compgeo.2014.12.004.

Khan, Iqbal H., and Syed I. Hasnain. “Engineering Properties of Sabkha Soils in the Benghazi Plain and Construction Problems.” Engineering Geology 17, no. 3 (October 1981): 175–183. doi:10.1016/0013-7952(81)90082-x.

Lai, Fengwen, Fuquan Chen, and Dayong Li. “Bearing Capacity Characteristics and Failure Modes of Low Geosynthetic-Reinforced Embankments Overlying Voids.” International Journal of Geomechanics 18, no. 8 (August 2018): 04018085. doi:10.1061/(asce)gm.1943-5622.0001206.

Alkhorshid, Nima Rostami, Gregório Luís Silva Araújo, and Ennio Marques Palmeira. “Behavior of Geosynthetic-Encased Stone Columns in Soft Clay: Numerical and Analytical Evaluations.” Soils and Rocks 41, no. 3 (December 24, 2018): 333–343. doi:10.28927/sr.413333.

Elsawy, M.B.D. “Behaviour of Soft Ground Improved by Conventional and Geogrid-Encased Stone Columns, Based on FEM Study.” Geosynthetics International 20, no. 4 (August 2013): 276–285. doi:10.1680/gein.13.00017.

Yoo, Chungsik. “Settlement Behavior of Embankment on Geosynthetic-Encased Stone Column Installed Soft Ground – A Numerical Investigation.” Geotextiles and Geomembranes 43, no. 6 (November 2015): 484–492. doi:10.1016/j.geotexmem.2015.07.014.

Almeida, Marcio S. S., Iman Hosseinpour, Mario Riccio, and Dimiter Alexiew. “Behavior of Geotextile-Encased Granular Columns Supporting Test Embankment on Soft Deposit.” Journal of Geotechnical and Geoenvironmental Engineering 141, no. 3 (March 2015): 04014116. doi:10.1061/(asce)gt.1943-5606.0001256.

Collin, J. G. "Column supported embankment design considerations." In Proceedings of the 52nd annual geotechnical engineering conference. Minnesota, (2004): 51-78.

Full Text: PDF

DOI: 10.28991/cej-2020-03091569


  • There are currently no refbacks.

Copyright (c) 2020 imad eddine debbabi

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.