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Acta Geotechnica

, Volume 12, Issue 5, pp 1089–1103 | Cite as

Failure modes and bearing capacity of strip footings on soft ground reinforced by floating stone columns

  • Haizuo Zhou
  • Yu Diao
  • Gang ZhengEmail author
  • Jie Han
  • Rui Jia
Research Paper

Abstract

This study evaluates the failure modes and the bearing capacity of soft ground reinforced by a group of floating stone columns. A finite difference method was adopted to analyze the performance of reinforced ground under strip footings subjected to a vertical load. The investigation was carried out by varying the aspect ratio of the reinforced zone, the area replacement ratio, and the surface surcharge. General shear failure of the reinforced ground was investigated numerically without the surcharge. The results show the existence of an effective length of the columns for the bearing capacity factors N c and N γ. When certain surcharge was applied, the failure mode of the reinforced ground changed from the general shear failure to the block failure. The aspect ratio of the reinforced zone and the area replacement ratio also contributed to this failure mode transition. A counterintuitive trend of the bearing capacity factor N q can be justified with a shift in the critical failure mode. An upper-bound limit method based on the general shear failure mode was presented, and the results agree well with those of the previous studies of reinforced ground. Equivalent properties based on the area-weighted average of the stone columns and clay parameters were used to convert the individual column model to an equivalent area model. The numerical model produced reasonable equivalent properties. Finally, a theoretical method based on the comparison of the analytical equations for different failure modes was developed for engineering design. Good agreement was found between the theoretical and numerical results for the critical failure mode and its corresponding bearing capacity factors.

Keywords

Bearing capacity Failure modes Finite difference method Limit analysis Stone columns 

List of symbols

μ

Posison’s ratio

η

Area replacement ratio

φs

Friction angle of soil

φc,

Friction angle of columns

φeq

Equivalent friction angle of reinforced zone

φeq*

Equivalent friction angle of reinforced zone

γs

Unit weight of soil

γc

Unit weight of columns

γeq

Equivalent unit weight of reinforced zone

qu

Bearing capacity of the footings

Nc, Nq, Nγ

Bearing capacity factors of the ground

E

Modulus of elasticity

L/B

Length of the columns/width of the footing

q

Surcharge on the ground

cu, c, cs

Cohesion of soil

cc

Cohesion of columns

ceq

Equivalent cohesion of reinforced zone

n

Stress concentration ratio

Le

Effective length of the columns

qcri

Critical surcharge

qu,block

Bearing capacity at block failure

Nq,block

Bearing capacity factor at block failure

Qbase

Base resistance of the reinforced ground

Qside

Side friction of the reinforced ground

Nc,s

Bearing capacity factor for clay

ca

Undrained columns–soil adhesion

dc

Depth factor

Notes

Acknowledgement

This research was funded by the National Natural Science Foundation of China (Grant No. 51378345). The authors appreciate the financial support.

References

  1. 1.
    Aboshi H, Ichimoto E, Enoki M, Harada K (1979) The compozer—a method to improve characteristics of soft clays by inclusion of large diameter sand columns. In: Proceedings of the international conference on soil reinforcement: reinforced earth and other techniques, ParisGoogle Scholar
  2. 2.
    Abusharar SW, Han J (2011) Two-dimensional deep-seated slope stability analysis of embankments over stone column-improved soft clay. Eng Geol 120(1–4):103–110. doi: 10.1016/j.enggeo.2011.04.002 CrossRefGoogle Scholar
  3. 3.
    Ambily A, Gandhi SR (2007) Behavior of stone columns based on experimental and FEM analysis. J Geotech Geoenviron Eng 133(4):405–415CrossRefGoogle Scholar
  4. 4.
    Bae WS, Shin BW, An BC, Kim JS (2002) Behaviors of foundation system improved with stone columns. In: The twelfth international offshore and polar engineering conference. International Society of Offshore and Polar Engineers, pp 675–678Google Scholar
  5. 5.
    Barksdale RD, Bachus RC (1983) Design and construction of stone columns. Report No. FHWA/RD, 83/026, Federal Highway Administration, Washington DCGoogle Scholar
  6. 6.
    Black J, Sivakumar V, Madhav M, Hamill G (2007) Reinforced stone columns in weak deposits: laboratory model study. J Geotech Geoenviron Eng 133(9):1154–1161CrossRefGoogle Scholar
  7. 7.
    Black J, Sivakumar V, Bell A (2011) The settlement performance of stone column foundations. Géotechnique 61(11):909–922CrossRefGoogle Scholar
  8. 8.
    Bouassida M, Hadhri T (1995) Extreme load of soils reinforced by columns the case of insolated column. Soils Found 35(1):21–35CrossRefGoogle Scholar
  9. 9.
    Bouassida M, Jellali B, Lyamin A (2015) Ultimate bearing capacity of a strip footing on ground reinforced by a trench. Int J Geomech 15(3):06014021. doi: 10.1061/(asce)gm.1943-5622.0000418 CrossRefGoogle Scholar
  10. 10.
    Bransby F, Randolph M (1999) The effect of embedment depth on the undrained response of skirted foundations to combined loading. Soils Found 39(4):19–33CrossRefGoogle Scholar
  11. 11.
    Brauns J (1978) Die anfangstraglast von schottersaulen im bindigen untergrund. Die Bautechnik 55(8):263–271Google Scholar
  12. 12.
    Castro J (2014) Numerical modelling of stone columns beneath a rigid footing. Comput Geotech 60:77–87CrossRefGoogle Scholar
  13. 13.
    Castro J (2016) An analytical solution for the settlement of stone columns beneath rigid footings. Acta Geotech 11(2):309–324CrossRefGoogle Scholar
  14. 14.
    Castro J, Sagaseta C (2009) Consolidation around stone columns. Influence of column deformation. Int J Numer Anal Meth Geomech 33(7):851–877CrossRefzbMATHGoogle Scholar
  15. 15.
    Castro J, Karstunen M, Sivasithamparam N (2014) Influence of stone column installation on settlement reduction. Comput Geotech 59:87–97CrossRefGoogle Scholar
  16. 16.
    Drescher A, Detournay E (1993) Limit load in translational failure mechanisms for associative and non-associative materials. Geotechnique 43(3):443–456CrossRefGoogle Scholar
  17. 17.
    Duncan J, Brandon T, Jian W, Park Y, Griffith T, Corton J, Ryan E (2007) Densities and friction angles of granular materials with standard gradations 21b and #57. Rep CPGR 45, Center for Geotechnical Practice and Research, Viriginia Polytechnic Institute, Blacksburg, VAGoogle Scholar
  18. 18.
    Edwards DH, Zdravkovic L, Potts DM (2005) Depth factors for undrained bearing capacity. Geotechnique 55(10):755–758. doi: 10.1680/geot.2005.55.10.755 CrossRefGoogle Scholar
  19. 19.
    Enoki M, Yagi N, Yatabe R, Ichimoto E (1991) Shearing characteristic of composite ground and its application to stability analysis. Deep Found Improv Des Constr Test ASTM STP 1089:19–31Google Scholar
  20. 20.
    Etezad M, Hanna AM, Ayadat T (2014) Bearing capacity of a group of stone columns in soft soil. Int J Geomech 15(2):04014043CrossRefGoogle Scholar
  21. 21.
    Fattah MY, Shlash KT, Al-Waily MJM (2011) Stress concentration ratio of model stone columns in soft clays. Geotech Test J 34(1):1Google Scholar
  22. 22.
    Greenwood DA (1970) Mechanical improvement of soils below ground surface. In: Proceedings conference on ground engineering. Institution of Civil Engineers, London, pp 11–22Google Scholar
  23. 23.
    Griffiths D (1982) Computation of bearing capacity factors using finite elements. Geotechnique 32(3):195–202CrossRefGoogle Scholar
  24. 24.
    Han J (2014) Recent research and development of ground column technologies. Proc ICE Ground Improv 168(4):246–264CrossRefGoogle Scholar
  25. 25.
    Han J, Ye SL (2001) Simplified method for consolidation rate of stone column reinforced foundation. J Geotech Geoenviron Eng 127(7):597–603. doi: 10.1061/(ASCE)1090-0241(2001)127:7(597) CrossRefGoogle Scholar
  26. 26.
    Han J, Ye SL (2002) A theoretical solution for consolidation rates of stone column-reinforced foundations accounting for smear and well resistance effects. Int J Geomech 2(2):135–151. doi: 10.1061/(ASCE)1532-3641(2002)2:2(135) CrossRefGoogle Scholar
  27. 27.
    Han J, Parsons RJ, Sheth RA, Huang J (2005) Factors of safety against deep-seated failure of embankments over deep mixed columns. In: Proceedings of deep mixing 2005 conference, vol 1, pp 231–236Google Scholar
  28. 28.
    Hanna AM, Etezad M, Ayadat T (2013) Mode of failure of a group of stone columns in soft soil. Int J Geomech 13(1):87–96. doi: 10.1061/(asce)gm.1943-5622.0000175 CrossRefGoogle Scholar
  29. 29.
    Hansen JB (1970) A revised and extended formula for bearing capacity. Dan Geotechn Inst Cph Bull 28:5–11Google Scholar
  30. 30.
    Hu W (1995) Physical modelling of group behaviour of stone column foundations. Ph.D. dissertation, University of Glasgow, Glasgow, UKGoogle Scholar
  31. 31.
    Hughes JMO, Withers NJ (1974) Reinforcing of soft cohesive soils with stone columns. Ground Eng 7(3):42–49Google Scholar
  32. 32.
    Hughes JMO, Withers NJ, Greenwood DA (1975) A field trial of the reinforcing effect of a stone column in soil. Geotechnique 25(1):31–44CrossRefGoogle Scholar
  33. 33.
    Itasca Consulting Group, Inc. (2006) FLAC3D – Fast Lagrangian Analysis of Continua in 3 Dimensions, Ver. 3.1, User’s Manual. Minneapolis, ItascaGoogle Scholar
  34. 34.
    Juran I, Guermazi A (1988) Settlement response of soft soils reinforced by compacted sand columns. J Geotechn Eng 114(8):930–943CrossRefGoogle Scholar
  35. 35.
    Killeen MM, McCabe BA (2014) Settlement performance of pad footings on soft clay supported by stone columns: a numerical study. Soils Found 54(4):760–776CrossRefGoogle Scholar
  36. 36.
    Ladd CC (1964) Stress-strain modulus of clay in undrained shear. J Soil Mech Found Div 90(5):103–132Google Scholar
  37. 37.
    Lee K, Randolph M, Cassidy M (2013) Bearing capacity on sand overlying clay soils: a simplified conceptual model. Géotechnique 63(15):1285–1297CrossRefGoogle Scholar
  38. 38.
    Madhav MR, Vitkar PP (1978) Strip footing on weak clay stabilized with a granular trench or pile. Can Geotech J 15(4):605–609CrossRefGoogle Scholar
  39. 39.
    McCabe B (2009) A review of field performance of stone columns on soft soils. In: Proceedings of ICE geotechnical engineeringGoogle Scholar
  40. 40.
    McKelvey D, Sivakumar V, Bell A, Graham J (2004) Modelling vibrated stone columns in soft clay. Proc ICE Geotech Eng 157(3):137–149CrossRefGoogle Scholar
  41. 41.
    Priebe HJ (1995) The design of vibro replacement. Ground Eng 28(10):31Google Scholar
  42. 42.
    Salgado R, Lyamin AV, Sloan SW, Yu HS (2004) Two- and three-dimensional bearing capacity of foundations in clay. Geotechnique 54(5):297–306. doi: 10.1680/geot.54.5.297.46720 CrossRefGoogle Scholar
  43. 43.
    Sexton B, McCabe B (2013) Numerical modelling of the improvements to primary and creep settlements offered by granular columns. Acta Geotech 8(4):447–464CrossRefGoogle Scholar
  44. 44.
    Sexton BG, McCabe BA, Castro J (2014) Appraising stone column settlement prediction methods using finite element analyses. Acta Geotech 9(6):993–1011CrossRefGoogle Scholar
  45. 45.
    Shahu JT, Reddy YR (2012) Clayey soil reinforced with stone column group: model tests and analyses. J Geotech Geoenviron Eng 137(12):1265–1274. doi: 10.1061/(ASCE)GT.1943-5606.0000552 CrossRefGoogle Scholar
  46. 46.
    Skempton AW (1951) The bearing capacity of clays. Proc Build Res Congr 1:180–189Google Scholar
  47. 47.
    Skempton AW (1959) Cast in situ bored piles in London clay. Geotechnique 9(4):153–173CrossRefGoogle Scholar
  48. 48.
    Stuedlein AW, Holtz RD (2011) Analysis of footing load tests on aggregate pier reinforced clay. J Geotech Geoenviron Eng 138(9):1091–1103CrossRefGoogle Scholar
  49. 49.
    Stuedlein AW, Holtz RD (2013) Bearing capacity of spread footings on aggregate pier reinforced clay. J Geotech Geoenviron Eng 139(1):49–58. doi: 10.1061/(ASCE)GT.1943-5606.0000748 CrossRefGoogle Scholar
  50. 50.
    Tan SA, Tjahyono S, Oo K (2008) Simplified plane-strain modeling of stone-column reinforced ground. J Geotech Geoenviron Eng 134(2):185–194CrossRefGoogle Scholar
  51. 51.
    Terzaghi K (1943) Theoretical soil mechanics. Wiley, New YorkCrossRefGoogle Scholar
  52. 52.
    Watts K, Johnson D, Wood L, Saadi A (2000) An instrumented trial of vibro ground treatment supporting strip foundations in a variable fill. Geotechnique 50(6):699–708CrossRefGoogle Scholar
  53. 53.
    White DJ, Pham HT, Hoevelkamp KK (2007) Support mechanisms of rammed aggregate piers. I: experimental results. J Geotech Geoenviron Eng 133(12):1503–1511CrossRefGoogle Scholar
  54. 54.
    Wood DM, Hu W, Nash DFT (2000) Group effects in stone column foundations: model tests. Geotechnique 50(6):689–698CrossRefGoogle Scholar
  55. 55.
    Zhang Z, Han J, Ye G (2014) Numerical investigation on factors for deep-seated slope stability of stone column-supported embankments over soft clay. Eng Geol 168:104–113CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • Haizuo Zhou
    • 1
    • 2
  • Yu Diao
    • 1
    • 2
  • Gang Zheng
    • 1
    • 2
    • 3
    Email author
  • Jie Han
    • 4
  • Rui Jia
    • 1
    • 2
  1. 1.School of Civil EngineeringTianjin UniversityTianjinChina
  2. 2.Key Laboratory of Coast Civil Structure SafetyTianjin University, Ministry of EducationTianjinChina
  3. 3.State Key Laboratory of Hydraulic Engineering Simulation and SafetyTianjin UniversityTianjinChina
  4. 4.Department of Civil, Environmental, and Architectural EngineeringUniversity of KansasLawrenceUSA

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