Reliability of piles bearing capacity methods based on CPT
DOI:
https://doi.org/10.24849/j.geot.2019.147.05Keywords:
Reliability, Bearing Capacity, FORMAbstract
This paper presents a reliability analysis of three semi-empirical methods to predict piles bearing capacity based on the First Order Reliability Method (FORM) with the objective of assessing the probability of such methods to estimate the bearing capacity against safety. The data of 25 CPT tests were carried out in a single site was considered in this study as well as the load test performed in a 0,25 m diameter and 8 m long bored pile installed in an unsaturated tropical sandy soil in the city of Bauru, state of São Paulo. The distributions of the random variables defined by the cone tip resistance (qc) and the sleeve friction (fs) measured by the CPT, as well as the end bearing resistance (Qp,ult) and ultimate lateral friction (Ql,ult) from the pile were adjusted to a normal probability distribution by the Kolmogorov-Smirnov statistical test. The reliability analysis indicated that the most appropriate method to use for the studied case is the one proposed by Aoki & Velloso, which provided probability estimative against security of 0,16%, while the other two methods only can be used after been adjusted.
Downloads
References
ABNT (1991). MB-3406 – Solo – Ensaio de Penetração de Cone In Situ (CPT), Rio de Janeiro, 11p.
ABNT (2010). NBR 6122 – Projeto e Execução de Fundações, Associação Brasileira de Normas Técnicas, Rio de Janeiro, RJ, Brasil.
Ahmad, A. R.; Madiai, C.; Vannucchi, G. (2003). Reliability of different methods in estimating bearing capacity and stiffness of single piles. Proceedings of BGA International Conference on foundation Innovations, Observations, Design and Practice. [S.l], p. 71-80.
Ang, H.-S. A.; Tang, H. W. (1975). Probability concepts in engineering planning and design. Illinois: John Wiley and Sons, v. 1 e 2.
Aoki, N.; Velloso, D. A. (1975). An Approximate Method to Estimate the Bearing Capacity of Piles. Proceedings of the 5th Pan American Conference on Soil Mechanics and Foundation Engineering. Buenos Aires. v. 1.
Bustamante, M.; Gianeselli, L. (1982). Pile Bearing Capacity Prediction by Means of Static Penetrometer CPT. In: Proceedings of the 2nd European Symposium on Penetration Testing, p. 493-500.
Cavalcante, E. H.; Danzinger, F. A.; Giacheti, H. L.; Coutinho, R. Q. (2007). Campos Experimentais Brasileiros. Revista Luso-Brasileira de Geotecnia, v. 111, p. 99-205.
De Mio, G. (2005). Condicionantes Geológicos na Interpretação de Ensaios de Piezocone para Identificação Estratigráfica na Investigação Geotécnica e Geoambiental. 348p. Tese de Doutorado. Escola de Engenharia de São Carlos - EESC/USP. São Carlos.
Fenton, G. A.; Griffiths, D. V. (2008). Risk Assessment in Geotechnical Engineering. Hoboken: John Wiley & Sons, Inc. ISBN 978-0-470-17820-1.
Hasofer, A. M.; Lind, N. C. (1974). Exact and Invariant Second Moment Code Format. Journal of Engineering Mechanics, v. 100(1), p. 111-121,.
Lobo, A. S. (1991). Colapsividade do Solo de Bauru e sua Influência em Estacas de Pequeno Porte. Tese de Doutorado. Escola de Engenharia de São Carlos - EESC/USP. São Carlos,.
Nogueira, C. G. (2010). Desenvolvimento de modelos mecânicos, de confiabilidade e de otimização para aplicação em estruturas de concreto armado. Universidade de São Paulo. São Carlos, p. 345.
Philipponnat, G. (1980). Méthode pratique de calcul d'un pieu isolé, à l'aide du pénétromètre statique. Revue Francaise de Geotechnique, n. 10, p. 55-64,.
Robertson, P. K.; Cabal, K. L. (2015). Guide to cone penetration testing. 6th Edition. Gregg Drilling & Testing, Inc. California.
Robertson, P. K.; Campanella, R. G.; Gillespie, D.; Greig, J. (1986). Use of piezometer cone data. In: Use of in situ tests in geotechnical engineering. ASCE, p. 1263-1280.
