Influence of Spatially Variable Side Friction and Collocated Data on Single and Multiple Shaft Resistances
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 139, Issue 1
Abstract
Reliability-based design, such as LRFD, aims at meeting desired probability of failure levels for engineered structures. The present work attempts to contribute to this field by analyzing the influence of spatially variable soil/rock strength on the axial resistance uncertainty of single and multiple shafts in group layouts. This includes spatial variability over the individual shaft surfaces, effects of limited data, random measurement errors, and workmanship. A possible correlation between boring data inside or near the footprint of a foundation and the foundation itself is considered. In a geostatistical approach, spatial averaging (upscaling) and a degenerate case of ordinary kriging are applied to develop variance reduction charts and design equations for a series of foundation group layouts (single, double, triple, and quadruple). For the potential situation of an unknown horizontal correlation range at a site, the worst case scenarios are identified and demonstrated in an example problem. Resulting probabilities of failure are applied to the whole foundation (i.e., group) rather than single objects. It is found that a boring at the center of a group footprint can significantly reduce resistance prediction uncertainty, especially under the worst case scenario for unknown horizontal correlation range. In contrast, independent of the presence of a center boring or not, the uncertainty reduction through additional borings becomes small, once four or five borings are available.
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Acknowledgments
This research was supported by the Florida Department of Transportation Contract No. BD-545, RPWO #76, entitled “Modification of LRFD Resistance Factors Based on Site Variability.” The boring and laboratory test results for the example problem were obtained by the State Materials Office of the Florida Department of Transportation. The first author also acknowledges support by a fellowship of the Bahia State Science Foundation (FAPESB; DCR 0001/2009), Brazil.
References
AASHTO. (2004). LRFD bridge design specifications, 3rd Ed., AASHTO, Washington, DC.
Brustamante, M., and Gianeselli, L. (1982). “Pile bearing capacity prediction by means of static penetrometer, CPT.” Proc., 2nd Eur. Symp. Penetrometer Test., Vol. 2, A.A. Balkema Publishers, Leiden, Netherlands 493–500.
Chung, J., Ko, J., Klammler, H., McVay, M., and Lai, P. (2011). “A numerical and experimental study of bearing stiffness of drilled shafts socketed in heterogeneous rock.” Comput. Struct., 90–91, 145–152.
Fenton, G. A., and Griffiths, D. V. (2002). “Probabilistic foundation settlement on spatially random soil.” J. Geotech. Geoenviron. Eng., 128(5), 381–390.
Fenton, G. A., and Griffiths, D. V. (2003). “Bearing-capacity prediction of spatially random c—φ soils.” Can. Geotech. J., 40(1), 54–65.
Fenton, G. A., and Griffiths, D. V. (2005). “Three-dimensional probabilistic foundation settlement.” J. Geotech. Geoenviron. Eng., 131(2), 232–239.
Fenton, G. A., Griffiths, D. V., and Cavers, W. (2005). “Resistance factors for settlement design.” Can. Geotech. J., 42(5), 1422–1436.
Fenton, G. A., Griffiths, D. V., and Zhang, X. Y. (2008). “Load and resistance factor design of shallow foundations against bearing failure.” Can. Geotech. J., 45(11), 1556–1571.
Florida Department of Transportation (FDOT). (2003). “Static and dynamic field testing of drilled shafts: Suggested guidelines on their use for FDOT structures.” Rep. No. 99052794, FDOT, Gainesville, FL.
Florida Department of Transportation (FDOT). (2011). Soils and foundations handbook, FDOT, Gainesville, FL.
Foye, K. C., Salgado, R., and Scott, B. (2006). “Assessment of variable uncertainties for reliability-based design of foundations.” J. Geotech. Geoenviron. Eng., 132(9), 1197–1207.
Haldar, S., and Sivakumar Babu, G. L. (2008). “Load resistance factor design of axially loaded pile based on load test results.” J. Geotech. Geoenviron. Eng., 134(8), 1106–1117.
Isaaks, E. H., and Srivastava, R. M. (1989). An introduction to applied geostatistics, Oxford University Press, Oxford, U.K.
Journel, A. G., and Huijbregts, C. J. (1978). Mining geostatistics, Blackburn Press, Caldwell, NJ.
Journel, A. G., and Rossi, M. E. (1989). “Do we need a trend model in kriging?” Math. Geol., 21(7), 715–739.
Kitanidis, P. K. (1997). Introduction to geostatistics: Applications to hydrogeology, Cambridge University Press, Cambridge, U.K.
Klammler, H., Hatfield, K., McVay, M., and Luz, J. (2011). “Approximate up-scaling of geo-spatial variables applied to deep foundation design.” Georisk. Assess. Manage. Risk Eng. Syst. Geohazards, 5(3–4), 163–172.
Klammler, H., McVay, M., Horhota, D., and Lai, P. (2010a). “Influence of spatially variable side friction on single drilled shaft resistance and LRFD resistance factors.” J. Geotech. Geoenviron. Eng., 136(8), 1114–1123.
Klammler, H., McVay, M., Lai, P., and Horhota, D. (2010b). “Incorporating geostatistical aspects in LRFD design for deep foundations.” ASCE Geotechnical Special Publication GeoFlorida 2010: Advances in Analysis, Modeling and Design (CD-ROM), E. O. Fratta, B. Muhunthan, and A. J. Puppala, eds., Vol. 199, ASCE, Reston, VA.
Paice, G. M., Griffiths, D. V., and Fenton, G. A. (1996). “Finite element modeling of settlements on spatially random soil.” J. Geotech. Eng., 122(9), 777–779.
Phoon, K. K., and Kulhawy, F. H. (1999a). “Characterization of geotechnical variability.” Can. Geotech. J., 36(4), 612–624.
Phoon, K. K., and Kulhawy, F. H. (1999b). “Evaluation of geotechnical variability.” Can. Geotech. J., 36(4), 625–639.
Phoon, K. K., Kulhawy, F. H., and Grigoriu, M. D. (2003). “Development of a reliability-based design framework for transmission line structure foundations.” J. Geotech. Geoenviron. Eng., 129(9), 798–806.
Popescu, R., Deodatis, G., and Nobahar, A. (2005). “Effects of random heterogeneity of soil properties on bearing capacity.” Prob. Eng. Mech., 20(4), 324–341.
Sivakumar Babu, G. L., Srivastava, A., and Murthy, D. S. N. (2006). “Reliability analysis of the bearing capacity of a shallow foundation resting on cohesive soil.” Can. Geotech. J., 43(2), 217–223.
Zhang, L. M., Tang, W. H., and Ng, C. W. W. (2001). “Reliability of axially loaded driven pile groups.” J. Geotech. Geoenviron. Eng., 127(12), 1051–1060.
Zhang, L. M., Xu, Y., and Tang, W. H. (2008). “Calibration of models for pile settlement analysis using 64 load tests.” Can. Geotech. J., 45(1), 59–73.
Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 139 • Issue 1 • January 2013
Pages: 84 - 94
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Nov 18, 2010
Accepted: Mar 12, 2012
Published online: Mar 14, 2012
Published in print: Jan 1, 2013
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