Earthquakes and Structures

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Contribution of raft to resist lateral loads in a piled raft foundation-Experimental findings

  • Jami, Irfan (Department of Civil Engineering, University of Engineering & Technology) ;
  • Ahmad, Irshad (Department of Civil Engineering, University of Engineering & Technology) ;
  • Ullah, Wali (Department of Civil Engineering, University of Engineering & Technology)
  • Received : 2021.03.11
  • Accepted : 2021.05.11
  • Published : 2021.09.25
⟨ Previous Next ⟩

Abstract

The Combined pile raft foundation (CPRF) is considered to be an efficient type for tall buildings since it accounts for raft contribution to both vertical and lateral loads. Traditionally, in a pile raft foundation, the contribution of raft to resist loads is ignored due to the fact that its analysis requires complicated soil-structure interaction. Hence this simplification may lead to an uneconomical design. While research on vertical resistance of raft in CPRF is considerable, research on its horizontal resistance is yet very limited. To address this issue, in this research the contribution of the components of pile-raft foundation to lateral loads is evaluated experimentally. Ten small scale combined piled raft models were fabricated and instrumented with load cells at pile top to find raft contribution in resisting vertical and lateral load. Load cells were composed of strain gauge rosettes in Wheatstone bridge arrangements. The vertical static load of 5350 N was applied through steel plates and the lateral incremental load of 1500 N was applied using the hydraulic machine. The number of piles was varied from 1 to 25 with s/d ratio of 6.67 and 3.44. The results show that raft in a piled raft system is contributing in resisting 10-60% of the applied lateral load which is highly dependent on the number of piles. The percentage contribution of the raft to the lateral load decreases with the increase in the number of piles. Furthermore, it was also shown that in case of piled raft, the rear piles are resisting more lateral load than the front piles depending on the vertical load level.

Keywords

References

  1. Bandyopadhyay, S., Sengupta, A. and Parulekar, Y.M. (2020), "Behavior of a combined piled raft foundation in a multilayered soil subjected to vertical loading", Geomech. Eng., 21(4), 379-390. https://doi.org/10.12989/gae.2020.21.4.379.
  2. Burland, J.B. (1995), "Piles as settlement reducers. keynote address" 18th Italian Congress on Soil Mechanics, Pavia, Italy.
  3. Deb, P. and Pal, S.K. (2020), "Nonlinear analysis of lateral load sharing response of piled raft subjected to combined VL loading", Marine Georesources Geotechnol., 1-21.
  4. Hamada, J., Tsuchiya, T., Tanikawa, T. and Yamashita, K. (2015), "Lateral loading tests on piled rafts and simplified method to evaluate sectional forces of piles", Geotech. Eng. J. SEAGS AGSSEA, 46(2), 29-42. https://doi.org/10.1080/1064119X.2020.1766607.
  5. Jamil, I. and Ahmad, I. (2019), "Bending moments in raft of a piled raft system using Winkler analysis", Geomech. Eng. 18(1), 41-48. https://doi.org/10.12989/GAE.2019.18.1.041.
  6. Jeong, S.S., Lee, J.H., Park, J.J., Roh, Y.H. and Hong, M.H. (2017), "Analysis of load sharing ratio of piled raft foundation by field measurement", J. Korean Geotech. Soc., 33(8), 41-52. https://doi.org/10.7843/kgs.2017.33.8.41.
  7. Katzenbach, R. and Turek, J. (2005), "Combined pile-raft foundation subjected to lateral loads", In Proceedings of the International Conference on Soil Mechanics and Geotechnical Engineering, 16(4), https://doi.org/10.3233/978-1-61499-656-9-2001.
  8. Khari, M., Kassim, K.A. and Adnan, A. (2013), "An experimental study on pile spacing effects under lateral loading in sand", Sci. World J., 2013. https://doi.org/10.1155/2013/734292.
  9. Khari, M., Kassim, K.A. and Adnan, A. (2014), "Sand samples' preparation using mobile pluviator", Arabian J. Sci. Eng., 39(10), 6825-6834. https://doi.org/10.1007/s13369-014-1247-8.
  10. Kulhawy, F.H., Trautmann, C.H., Beech, J.F., O'Rourke, T. D., McGuire, W., Wood, W.A. and Capano, C. (1983), Transmission line structure foundations for uplift-compression loading Report EL-2870, Electric Power Research Institute, Palo Alto, Calif.
  11. Matsumoto, T., Nemoto, H., Mikami, H., Yaegashi, K., Arai, T. and Kitiyodom, P. (2010), "Load tests of piled raft models with different pile head connection conditions and their analyses", Soils Found., 50(1), 63-81. https://doi.org/10.3208/sandf.50.63
  12. Merin Jose, K., Krishnan, D. and Ravichandran, P.T. (2020), "Behaviour of vertically loaded piled raft system", J. Comput. Theoretic. Nanosci., 17(5), 2383-2387. https://doi.org/10.1016/j.matpr.2020.05.496.
  13. Mohammadi, S.D., Nikoudel, M.R., Rahimi, H. and Khamehchiyan, M. (2008), "Application of the Dynamic Cone Penetrometer (DCP) for determination of the engineering parameters of sandy soils", Eng. Geology, 101(3-4), 195-203. https://doi.org/10.1016/J.ENGGEO.2008.05.006
  14. Poulos, H.G. (2001), Methods of Analysis of Piled Raft Foundations, A Report Prepared on Behalf of Technical Committee TC18 of Piled Foundations.
  15. Prakash, S. (1962), Behavior of Pile Groups Subjected to Lateral Loads, University of Illinois.
  16. Randolph, M.F. (1994), "Design methods for pile groups and piled rafts", Proc.XIII ICSMFE, New Delhi, 5, 61-82,
  17. Shahadat Hossain, M. (2009), "Determination of Relative Density of Sand Using Dynamic Cone Resistance Data", Master Thesis, BUET, Dhaka, Bangladesh.
  18. Stacul, S., Squeglia, N. and Russo, G. (2020), "PRaFULL: A method for the analysis of piled raft foundation under lateral load", Geomech. Eng., 20(5), 433-445. https://doi.org/10.12989/gae.2020.20.5.433.
  19. Tech Note TN-505-06 (2018), "Strain Gage Selection: Criteria, Procedures, Recommendations, Vishay Precision Group; Windell, U.S.A. http://www.vishaypg.com
  20. Unsever, Y.S., Matsumoto, T. and Ozkan, M.Y. (2015), "Numerical analyses of load tests on model foundations in dry sand", Comput. Geotech., 63, 255-266. https://doi.org/10.1016/j.compgeo.2014.10.005.
  21. Vu, A.T., Matsumoto, T., Yoshitani, R. and Nguyen, T.L. (2017), "Behavior of pile group and piled raft foundation models having batter piles", J. Earth Eng., 2(1), 27-40.
  22. Yilmaz, B. (2010), An Anlaytical and Experimental Study on Piled Raft Foundations", Master Thesis, METU, Ankara, Turkey.