Acta Geotechnica

, Volume 8, Issue 1, pp 17–31 | Cite as

Experimental investigations and analysis on different pile load testing procedures

Research Paper

Abstract

The paper presents experimental results of two Osterberg’s cell load tests (OLTs) and three conventional load tests (COLTs) in the same subsoil conditions on Continuous Flight Auger (CFA) piles carefully monitored during construction stages. The instrumentation along the pile shaft in all the tests allows interesting comparisons of both global behaviour and local load transfer. Significant differences in the stiffness of the soil-pile system with the different test procedures is outlined. The main differences between the two test procedures occur at the two opposite ends of the pile, as could have been expected, while the observed behaviour in the middle part of the tested piles is close for the two models. A relatively simple FEM model has been calibrated on the basis of the OLTs results. The same model is capable of accurately matching the experimental results of the COLTs, proving that the observed differences are not due to random factors. Furthermore, the same model has been used to simulate ideal load tests. Such a reliable simulation shows that both the experimental procedures are actually responsible for significant differences in the behaviour of the soil-pile system even in the simple case of a concentrated axial load. Large differences arise in terms of the stiffness of the system with the OLTs providing by far the stiffest response. Despite being intermediate between the OLT and the ILT, the COLTs provide a response of the pile-soil system, which is on the average about two times stiffer than the Ideal test, where the force applied on top of the pile does not depend on a tangible reaction system. Care should be thus taken when considering the results of such tests in the prediction of the settlement of a piled foundation. Correction factors should be applied to the experimentally observed behaviour.

Keywords

Kentledge Load test Osterberg Pile Stiffness 

References

  1. 1.
    England M (2003) Bi-directional static load testing—State of art. In: Proceedings of 4th international geotechnical seminar on deep foundations on BAP, Ghent, Belgium, June 2003, pp 309–313Google Scholar
  2. 2.
    Kraft L, Ray RP, Kagawa T (1981) Theoretical t-z curve. J Geotech Eng Div Asce 108(11):1543–1560Google Scholar
  3. 3.
    Kulhawy FH, Mayne PW (1990) Manual on estimating soil properties for foundation design. Research Project 1493-6, Electric Power Research Institute, Palo Alto, CaliforniaGoogle Scholar
  4. 4.
    Lizzi F (1976) Pieux de fondation fondedile à cellule de precharge. Construction, n. 6, Paris, pp 32–38Google Scholar
  5. 5.
    Lizzi F, Viggiani C, Vinale F (1983) Some experiences with pre-loading cells at the base of large diameter bored piles. In: Proceedings of VII Asian reg. conf. soil mech. found. eng, Haifa, pp 265–270Google Scholar
  6. 6.
    Mancuso C, Mandolini A, Silvestri F, Viggiani C (1999) Prediction and performance of axially loaded piles under working loads. In: Lo Presti D (ed) Proceedings of II international symposium on prefailure deformation of geomaterials, Torino, vol 1. Balkema, Rotterdam, pp 801–808Google Scholar
  7. 7.
    Mandolini A, Russo G, Viggiani C (2005) Pile foundations: experimental investigations, analysis and design. State of the Art Report. In: Proceedings of the sixteenth international conference on soil mechanics and geotechnical engineering, vol I. Osaka, Japan, pp 123–168Google Scholar
  8. 8.
    Osterberg JO (1984) A new simplified method for load testing drilled shafts. Found Drill 23(6) (July/August 1984, pub. Association of Drilled Shaft Contractors, ADSC, pp 9–11)Google Scholar
  9. 9.
    Osterberg JO (1989) Breakthrough in load testing methodology. Found Drill Ed ADSC 28(8):13Google Scholar
  10. 10.
    Osterberg JO (2001) Load testing high capacity piles. What have we learned? In: Proceedings of Vth international conference on deep foundational practice, April, 2001Google Scholar
  11. 11.
    Poulos HG (1998) Pile testing-from the designer’s viewpoint. In: Proceedings of 2nd international statnamic seminar, Tokyo, pp 3–22Google Scholar
  12. 12.
    Poulos HG, Carter JP, Small JC (2001) Foundations and retaining structures—research and practice, vol 4. In: Proceedings of XV ICSMGE, Istanbul, pp 2527–2606Google Scholar
  13. 13.
    Randolph MF (2003) Science and empiricism in pile foundations design. Géotechnique 53(10):847–875Google Scholar
  14. 14.
    Russo G (2004) Full scale load tests on instrumented micropiles. J Geotech Eng ICE 57(GE3):127–137Google Scholar
  15. 15.
    Russo G, Recinto B, Viggiani C, de Sanctis L (2003) A contribution to the analysis of Osterberg’s cell load test. In: Proceedings of 4th international geotechnical seminar on deep foundations on bored and auger piles, Ghent, Belgium, June 2003, pp 331–338Google Scholar
  16. 16.
    Schmertmann JH (1975) Measurement of in situ shear strength. State of the art report. ASCE speciality conference on in situ measurements of soil properties, vol 2, pp 57–138Google Scholar
  17. 17.
    Schmertmann JH, Hayes JA (1997) The Osterberg cell and bored pile testing—a symbiosis. The third international geotechnical engineering conference, Cairo, EgyptGoogle Scholar
  18. 18.
    Simons MH (1961) Discussion session 3B. In: Proceedings of V ICSMFE, Paris, vol 3, pp 257–261Google Scholar
  19. 19.
    Van Weele AF (1988) Cast in situ piles. Installation methods, soil disturbance and resulting pile behaviour. In: Proceedings of I seminar on deep foundations on bored and auger piles, Ghent, June 1988, pp 219–232Google Scholar
  20. 20.
    Viggiani C (1989) Influenza dei fattori tecnologici nel progetto dei pali di fondazione. Panel report, Sess. 1, XVII Italian geotechnical conference, Taormina, pp 232–238Google Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.University of Napoli Federico IINaplesItaly

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