Structural Engineering and Mechanics

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Effect of pile group geometry on bearing capacity of piled raft foundations

  • Fattah, Mohammed Y. (Department of Building and Construction Engineering University of Technology) ;
  • Yousif, Mustafa A. (Civil Engineering Department, Al-Mustansiriya University) ;
  • Al-Tameemi, Sarmad M.K. (Civil Engineering Department, Al-Mustansiriya University)
  • Received : 2014.04.02
  • Accepted : 2014.11.06
  • Published : 2015.06.10
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Abstract

This is an experimental study to investigate the behaviour of piled raft system in different types of sandy soil. A small scale "prototype" model was tested in a sand box with load applied to the foundation through a compression jack and measured by means of load cell. The settlement was measured at the raft by means of dial gauges, three strain gauges were attached on piles to measure the strains and calculate the load carried by each pile in the group. Nine configurations of group ($1{\times}2$, $1{\times}3$, $1{\times}4$, $2{\times}2$, $2{\times}3$, $2{\times}4$, $3{\times}3$, $3{\times}4$ and $4{\times}4$) were tested in the laboratory as a free standing pile group (the raft not in contact with the soil) and as a piled raft (the raft in contact with the soil), in addition to tests for raft (unpiled) with different sizes. It is found that when the number of piles within the group is small (less than 4), there is no evident contribution of the raft to the load carrying capacity. The failure load for a piled raft consisting of 9 piles is approximately 100% greater than free standing pile group containing the same number of piles. This difference increases to about 4 times for 16 pile group. The piles work as settlement reducers effectively when the number of piles is greater than 6 than when the number of piles is less than 6. The settlement can be increased by about 8 times in ($1{\times}2$) free standing pile group compared to the piled raft of the same size. The effect of piled raft in reducing the settlement vanishes when the number of piles exceeds 6.

Keywords

References

  1. ASTM D3080 (1998), "Standard Test Method for Direct Shear Test of Soils under Consolidated Drained Conditions", American Society of Testing and Materials.
  2. ASTM D422 (2001), "Standard Test Method for Particle Size-Analysis of Soils", American Society of Testing and Material.
  3. ASTM D4253 (2000), "Standard Test Method for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table", American Society of Testing and Materials.
  4. ASTM D4254 (2000), "Standard Test Method for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density", American Society of Testing and Materials.
  5. ASTM D854 (2005), "Standard Test Method for Specific Gravity of Soil Solids by Water Pycnometer", American Society of Testing and Materials.
  6. Bieganousky, W.N. and Marcuson, W.F. (1976), "Uniform placement of sand", J. Geotech. Eng. Div., ASCE, 102(3), 229-233.
  7. Burland, J.B., Broms, B.B. and de Mello, V.F.B. (1977), "Behaviour of foundations and structures", Proc. 9th ICSMFE, Tokyo, 2, 495-546.
  8. Chin, F.K. (1970), "Estimation of the ultimate load of piles not carried to failure", Proceedings of the 2nd Southeast Asian Conference on Soil Engineering, 81-90.
  9. Cox, W.R., Dixon, D.A. and Murphy, B.S. (1984), "Lateral-Load Tests on 25.4-mm (1-in.) Diameter Piles in Very Soft Clay in Side-by-Side and in-Line Groups", Laterally Loaded Deep Foundations: Analysis and Performance, ASTM STP 835, 122-139.
  10. Davis, E.H. and Poulos, H.G. (1972), "Rate of settlement under two-and three-dimensional conditions", Geotechnique, 22(1), 95-114. https://doi.org/10.1680/geot.1972.22.1.95
  11. Davisson, M.T. (1972), "High capacity piles", Proceedings of Lecture Series on Innovations in Engineering Construction, ASCE Illinois section, Chicago, March.
  12. DeBeer, E.E. (1968), "Proefondervindlijke bijdrage tot de studie van het grensdraag vermogen van zand onder funderingen op staal", Tijdshift der Openbar Verken van Belgie, No. 6, 1967 and No. 4, 5, and 6, 1968, cited by Fellenius 2009.
  13. Fellenius, B.H. (2009), Basics of Foundation Design, Book Electronic.
  14. Hansen, B. (1970), A Revised and Extended Formula for Bearing Capacity, Bulletin of the Danish Geotechnical Institute, Copenhagen, No. 28.
  15. Hartmann, F. and Jahn, P. (2001), Boundary Element Analysis of Raft Foundations on Piles, Kluwer Academic Publishers, Netherlands.
  16. Hooper, J.A. (1973), "Observations on the behaviour of a piled raft foundation in London clay", Proceeding of Institution of Civil Engineers, 55(2), 855-877. https://doi.org/10.1680/iicep.1973.4144
  17. Katzenbach, R. and Reul, O. (1997), "Design and performance of piled rafts", Proceeding XIVth ICSMFE, Hamburg, 4, 2253-2256.
  18. Mandolini, A., Russo, G. and Viggiani, C. (2005), "Pile foundations: experimental investigations", Proc. XVI ICSMGE, 1, Osaka, Japan.
  19. Prakoso, W.A. and Kulhawy, F.H. (2001), "Contribution to Piled Raft Foundation Design", J. Geotech. Geoenviron. Eng., ASCE, 127(1), 17-24. https://doi.org/10.1061/(ASCE)1090-0241(2001)127:1(17)
  20. Randolph, M.F. (1994), "Design methods for pile groups and piled rafts", Proc. 13th Int. Conf. on Soil Mechanics and Foundation Engineering, Int. Society for Soil Mechanics and Foundation Engineering, 5, 61-82.
  21. Reul, O. (2004), "Numerical study of the bearing behaviour of piled rafts", Int. J. Geomech., ASCE, 4(2), 59-68. https://doi.org/10.1061/(ASCE)1532-3641(2004)4:2(59)
  22. Reul, O. and Randolph, M.F. (2003), "Piled rafts in overconsolidated clay: comparison of in situ measurements and numerical analysis", Geotechnique, 53(3), 301-315. https://doi.org/10.1680/geot.2003.53.3.301
  23. Russo, G. (1998), "Numerical analysis of piled rafts", Int. J. Numer. Anal. Meth. Geomech., 22(6), 477-493. https://doi.org/10.1002/(SICI)1096-9853(199806)22:6<477::AID-NAG931>3.0.CO;2-H
  24. Sanctis, L. and Russo, G. (2008), "Analysis and performance of piled rafts designed using innovative criteria", J. Geotech. Geoenviron. Eng., ASCE, 134(8), 1118-1128. https://doi.org/10.1061/(ASCE)1090-0241(2008)134:8(1118)
  25. Shelke, A. and Patra, N.R. (2008), "Effect of arching on uplift capacity of pile groups in sand", Int. J. Geomech., ASCE, 8(6), 347-354. https://doi.org/10.1061/(ASCE)1532-3641(2008)8:6(347)
  26. Small J.C. and Liu L.S. (2008), "Time-settlement behaviour of piled raft foundations using infinite elements", Comput. Geotech., 35, 187-195. https://doi.org/10.1016/j.compgeo.2007.04.004
  27. Su, Q., Mayao, C., Bin, W. and Bai, H. (2011), "The load sharing and it's time effect of the piled raft foundation under high embankment", ICTE 2011, ASCE, 1396-1402.
  28. Turner, J.P. and Kulhawy, F.H. (1987), "Experimental analysis of drilled foundations subjected to repeated axial loads under drained conditions", Report EL-5325, Electric Power Research Institute, Palo Alto, California.
  29. Winterkorn, H.F. and Fang, H.Y. (1975), Foundation Engineering Hand Book, Van Nostrand Reinhold Company, New York.
  30. Yilmaz, B. (2010), "An analytical and experimental study on piled raft foundations", MSc. Thesis, Middle East Technical University, Ankara.
  31. Xia, R., Doleze, V., Rak, L., Qian, H. and Rao, B. (2009), "Geotechnical design of a partially piled raft foundation", International Foundation Congress and Equipment, ASCE, 223-230.
  32. Zeevaert, L. (1957) "Compensated friction-pile foundation to reduce the settlement of buildings on highly compressible volcanic clay of Mexico City", Proc. 4th ICSMFE, London.
  33. Zhang, U., Zhang, X., Ma, Y., Zhang, X. and Yang, S. (2014), "Large-scale pilot test study on bearing capacity of sea- crossing bridge main pier pile foundations", Geomech. Eng., 7(2), 201-2012. https://doi.org/10.12989/gae.2014.7.2.201

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