Evaluation of Distinct Factor Affecting the Bearing Capacity in Ground Improvement with Stone Column Group

مهندسی عمران فردوسی

Article 8, Volume 32, Issue 1 - Serial Number 25, April 2019, Pages 137-150   

Document Type: Research Note

DOI: 10.22067/civil.v32i1.61713

Authors

Saeed Ghaffarpour jahromi^{* 1}; Saeed Gharbanbeygi²; Mojtaba Yaghoubi¹

¹Shahid Rajaee Teacher Training University

²Shahid Beheshti Unversity

Abstract

Increasing construction industry and the need to build structures on lands that do not have sufficient load-bearing capacity resulted in the development of soil improvement techniques to enhance site capability. The use of stone columns for the ground improvement for reasons such as environmental compatibility, cost effective, minimizing the liquefaction potential of the ground, settlement reduction, increase of the load-bearing capacity and significant reduction in the period of consolidation is considered as one of the most effective soft soil reinforcement methods. Stone columns can be designed to bear on the hard stratum or as a floating system where the toe is embedded in the soft layer. What in recent years were as the basis for designing of groups of stone columns were based on the theories developed for single stone columns ignoring the group interaction. Most of the existing design methods for stone columns adopt unit cell idealization which is not applicable to spread footing. To assess the influence of various parameters on the performance of a group of stone columns, in this paper which is based on the finite element method, the effect of hardness and resistance parameters affecting the load bearing capacity was discussed. More than 140 analyses of different parameters of soil and stone columns were carried out and were discussed in the form of graphs to compare the effects of these parameters. Results showed that using stone columns had a significant impact on increasing the bearing capacity of the soft grounds. The rate of growing enhances with increase of replacement ratio of stone columns into the soft soil due to group interaction. Increase of elasticity and internal friction angle of column materials as well as soil Poisson's ratio have a significant impact on increasing load-bearing capacity on the other hand when Poisson's ratio of stone columns increases any substantial change isn’t see. In addition of bearing capacity increase, growth of replacement ratio enhances the impact of strength and stiffness parameters of soil and columns on bearing capacity increase which shows the influence of the group interaction. End bearing columns were observed as a factor influencing the increase of bearing capacity and intensifying the effect of stiffness and strength parameters on column bearing capacity.

Keywords

Stone Columns; Bearing Capacity; Finite Element Method; Ground Improvement; Group Effect

References

1. قضاوی، محمود و نظری‌ افشار، جواد، «طراحی و روش‌های اجرای ستون‌های سنگی»، انتشارات دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، (1388)

2. Guetifa Z., Bouassidaa M. and Debatsb J., "Improved Soft Clay Characteristics due to Stone Column Installation", Computers and Geotechnics, Vol. 34, No. 2, Pp. 104–111, (2007).

3. Etezad, M., "Geotechnical Performance of Group of Stone Columns", PhD Thesis, Concordia University, Montreal, Canada (2007).

4. Balaam N. and Booker J. R., "Effect of Stone Column Yield on Settlement of Rigid Foundations in Stabilized Clay", International Journal for Numerical and Analytical Methods in Geomechanics, Vol. 9, No. 4, Pp. 331–351, (1985).

5. Bae, W., Bang, W. and Byung, C., "Behavior of Foundation System Improved with Stone Columns", Proc., 12th Int. Offshore and Polar Engineering Conf., Int. Society of Offshore and Polar Engineers, Cupertino, CA, (2002).

6. Wehr, W., "Stone Columns-single Columns and Group Behavior", Proc. 5th Int. Conf. on Ground Improvement Techniques, Malaysia, Pp. 329–340, (2004).

7. Ambily, A. P. and Gandhi, S. R., "Behavior of Stone Columns based on Experimental and FEM Analysis", Journal of Geotechnical and Geoenvironmental Engineering, Vol. 133, No. 4, ASCE, Pp. 405-415, ( 2007).

8. Andreou, P. and Papadopoulos, V., "Modelling Stone Columns in Soft Clay", Proc. 6th European Conf. on Numerical Methods in Geotechnical Engineering, Graz, Pp. 777–780, (2006).

9. Kirsch, F., "Evaluation of Ground Improvement by Groups of Vibro Stone Columns Using Field Measurements and Numerical Analysis", Proc. of the 2nd Int. Workshop on the Geotechnics of Soft Soils, Glasgow, Pp. 241–248, (2008).

10. Micheal, K., "Numerical Modelling of Small Groups of Stone Columns", Ph.D. Thesis, National University of Ireland, Galway, (2012).

11. Hanna, A., Etezad, M. and Ayadat, T., "Mode of Failure of a Group of Stone Columns in Soft Soil", International Journal of Geomechanics, Vol. 13, Pp. 87-96, (2013).

12. Hughes, J. and Withers, N., "Reinforcing of Soft Cohesive Soils with Stone Columns", Ground Eng., Vol. 7, No.3, Pp. 42-49, (1974).

13. Christoulas, S., "An Experimental Study on Model Stone Columns", Soils and Foundations, Vol. 40, No. 6, Pp. 12-22, (2000).

14. McKelvey, D., Sivakumar, V., Bell, A. and Graham, J., "Modelling Vibrated Stone Columns in Soft Clay", Proc. Institution of Civil Engineers - Geotechnical Engineering, Vol. 157, No. 3, Pp. 137–149, (2004).

15. Hu, W., Wood, D. M. and Stewart, W., "Ground Improvement Using Stone Column Foundations: Result of Model Tests", Int. Conf. on Ground Improvement Techniques, CI-Premier, Singapore, Pp. 247-256, (1997).

16. Murugesan, S. and Rajagopal, K., "Geosynthetic-encased Stone Columns: Numerical Evaluation", Geotextiles and Geomembranes, Vol. 24, Pp. 349-358, (2006).

17. Wood, D., Hu, W. and Nash, D., "Group Effects in Stone Column Foundations: Model Tests", Geotechnique, Vol. 50, No. 6, Pp. 689-698, (2000).

18. Hu, W., "Physical Modeling of Group Behavior of Stone Column Foundations", Ph.D. dissertation, Univ. of Glasgow, U.K, (1995).

19. Mccabe, B., Mcneill, J. and Black, J., "Ground Improvement Using the Vibro-stone Column Technique", Transactions of the Institution of Engineers of Ireland, Galway, (2007).

20. Rao, N., Madhiyan, S. M. and Prasad, Y. V. S. N., "Influence of Bearing Area on the Behaviour of Stone Columns", Indian Geotechnical Conf., Calcutta: Pp. 235–237, (1992).

21. Malarvizhi S. and Ilamparuthi K. "Modeling of Geogrid Encased Stone Column", ICCMS-05, IIT Guwahati, India.A. Author 1 and B. Author 2, "Title of the Conference Paper", Proc. Int. Conf. on Power System Reliability. Singapore, Pp. 100-105, (2005).

22. ارجمند، محمدعلی و زمانی، مجید، «بررسی تأثیر ستون‌های سنگی بر ظرفیت باربری شالوده‌های سطحی ساختمان‌های با ارتفاع متوسط»، کنفرانس ملی مهندسی عمران و محیط زیست، قزوین (1394).

23. Nima, R., Nalbantoglu, Z. and Araujo, G., "3D Analysis of Full Scale Stone Column Reinforced Soft Clay: Numerical Evaluation", COBRAMSEG 2014, Goiânia, Vol. 1, (2014).