Bi-directional test: characteristics, interpretation and case studies of cast-in-situ piles in Brazil
DOI:
https://doi.org/10.24849/j.geot.2018.143.03Keywords:
Bi-directional test, O-cell, Pile load test, Load-settlement curveAbstract
The bi-directional test (Silva, 1983) has been increasingly used to verify the behavior of axially loaded piles. There are various interpretation methodologies to obtain the equivalent top-down load-settlement curve (conventional static load test), however, there are still no clear application guidelines in Brazil. After a brief history and a description of the test, the paper presents case studies of three cast-in-situ piles (drilled and root piles), in which the “traditional method” (Silva, 1983; 1986; Osterberg, 1995) and the method of Massad (2015) were applied. In addition to these, the Fleming (1992) solutions were applied, similar to the methodology of England (2005; 2009). The results were coherent with estimates by semi-empirical methods based on SPT data, in terms of bearing capacity, and with dynamic load test results, available in one case study. It's concluded that, for short or rigid piles, the methods presented are adequate. The method of Massad (2015) and the applied one based on Fleming (1992) are more realistic, since they consider the pile compressibility.
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References
ABNT NBR 6122 (2010). Norma Brasileira: Projeto e execução de fundações. Associação Brasileira de Normas Técnicas, Rio de Janeiro, Brasil, 91 p.
ABNT NBR 6118 (2014). Norma Brasileira: Projeto de estruturas de concreto – Procedimento. Associação Brasileira de Normas Técnicas, Rio de Janeiro, Brasil, 238 p.
Amir, J. M. (1983). Interpretation of load tests on piles in rock. Proceedings of 7th Asian Regional Conference on Soil Mechanics and Foundation Engineering, vol. 1, pp. 235-238, Haifa, Israel.
Aoki, N.; Velloso, D. A. (1975). An approximate method to estimate the bearing capacity of piles. Proceedings of 5th Pan-American Conference on Soil Mechanics and Foundations Engineering, vol. 1, pp. 367-376, Buenos Aires, Argentina.
Cabral, D. A. (1986). O uso da estaca raiz como fundação de obras normais. Anais do 8º Congresso Brasileiro de Mecânica dos Solos e Engenharia de Fundações – COBRAMSEF, vol. 6, pp. 71-82, Porto Alegre, Brasil.
Chin, F. K. (1970). Estimation of the ultimate load of piles from tests not carried to failure. Proceedings of 2nd Southeast Asian Conference on Soil Engineering, pp. 81-90, Singapore.
Chin, F. K. (1971). Discussion of Pile Tests – Arkansas River Project. Journal of the Soil Mechanics and Foundations Division, vol. 97, nº 6, pp. 930-932.
Cintra, J. C. A.; Aoki, N. (2010). Fundações por Estacas: Projeto Geotécnico. 1ª edição, Oficina de Textos, São Paulo, Brasil.
Coyle, H. M.; Reese, L. C. (1966). Load transfer for axially loaded piles in clay. Journal of the Soil Mechanics and Foundations Division, vol. 92, nº 2, pp. 1-26.
Décourt, L. (1982). Prediction of the bearing capacity of piles based exclusively on N values of the SPT. Proceedings of 2nd ESOPT – European Symposium on Penetrating Test, vol. 1, pp. 29-34, Amsterdam, Netherlands.
Décourt, L. (2016). Análise e Projeto de Fundações Profundas: Estacas. In: HACHICH, W. C. et al. Fundações: Teoria e Prática, 3ª Edição, PINI/ ABMS/ ABEF, São Paulo, Brasil. Cap. 8.1, pp. 263-297.
Décourt, L.; Quaresma, A. R. (1978). Capacidade de carga de estacas a partir de valores de SPT. Anais do 6º Congresso Brasileiro de Mecânica dos Solos e Engenharia de Fundações – COBRAMSEF, vol. 1, pp. 45-53, Rio de Janeiro, Brasil.
England, M. (2005). A conservative method of analysis of test results from bi-directional static load tests. Proceedings of 10th Baltic Geotechnical Conference, Riga, Latvia, www.loadtest.com/INT_media/media.htm.
England, M. (2009). Review of methods of analysis of test results from bi-directional static load tests. Proceedings of 5th International Symposium on Deep Foundations on Bored and Auger Piles, Ghent, Belgium, ISBN 978-0-415-47556-3.
Fellenius, B. H. (2014). Analysis of Results from Routine Static Loading Tests with Emphasis on the Bidirectional Test. Anais do 17º Congresso Brasileiro de Mecânica dos Solos e Engenharia Geotécnica – COBRAMSEG, Goiânia, Brasil.
Fellenius, B. H. (2017). Basics of Foundation Design. Electronic Edition, Sidney, Canada, www.fellenius.net.
Fleming, W. G. K. (1992). A new method for single pile settlement prediction and analysis. Géotechnique, vol. 42, nº 3, pp. 411-425.
Fugro Loadtest (2017). O-cell Technology. www.loadtest.com/services_int/ocelltechnology.htm.
Gibson, G. L.; Devenny, D. W. (1973). Concrete to bedrock bond testing by jacking from bottom of a bore hole. Canadian Geotechnical Journal, vol. 10, nº 2, pp. 304-306.
Horvath, R. G.; Kenney, T. C.; Kozicki, P. (1983). Methods of improving the performance of drilled piers in weak rock. Canadian Geotechnical Journal, vol. 20, nº 4, pp. 758-772.
Kim, S.; Chung, S. (2012). Equivalent head-down vs. movement relationships evaluated from bi-directional pile load tests. KSCE Journal of Civil Engineering, vol. 16, nº 7, pp. 1170-1177.
Kwon, O. S.; Choi, Y.; Kwon, O.; Kim, M. (2005). Comparison of the bi-directional load test with the top-down load test. Journal of the Transportation Research Board, Washington, nº 1936, pp. 108-116.
Lee, J.; Park, Y. (2007). Equivalent pile load–head settlement curve using a bi-directional pile load test. Computers and Geotechnics, vol. 35, nº 2, pp. 124-133.
Leonards, G. A.; Lovell, D. (1979). Interpretation of load tests on high-capacity driven piles. Behavior of Deep Foundations, ASTM STP 670, Raymond Lundgren, Ed., ASTM, pp. 388-415.
Massad, F. (2012). Resistência ao cisalhamento e deformabilidade dos solos sedimentares de São Paulo. Twin Cities – Solos das Regiões Metropolitanas de São Paulo e Curitiba, pp. 109-135, São Paulo, Brasil.
Massad, F. (2015). On the interpretation of the bidirectional static load test. Soils & Rocks, vol. 38, nº 3, pp. 249-262.
Mission, J.; Kim, H. (2011). Design charts for elastic pile shortening in the equivalent top-down load-settlement curve from a bidirectional load test. Computers and Geotechnics, vol. 38, nº 2, pp. 167-177.
Nguyen, H. M.; Puppala, A. J.; Patil, U. D.; Mosadegh, L.; Banerjee, A. (2017). Multi-Level O-cell tests on instrumented bored piles in the Mekong Delta. Geotechnical Frontiers 2017, Geotechnical Special Publication Number 279, Orlando, Florida, USA, ISBN: 978-1-5108-3950-2.
Monteiro, M. D.; Gurgueira, M. D.; Rocha, H. C. (2012). Geologia da Região Metropolitana de São Paulo. Twin Cities – Solos das Regiões Metropolitanas de São Paulo e Curitiba, pp. 17-46, São Paulo, Brasil.
Osterberg, J. O. (1989). New device for load testing driven piles and drilled shafts separates friction and end bearing. Proceedings of 14th International Conference of Piling and Deep Foundation, vol. 1, pp. 421-427, London, England.
Osterberg, J. O. (1995). The Osterberg Cell for loading testing drilled shafts and driven piles. FHWA-SA-94-035/ PB95-209508, Federal Highway Administration, U.S. Department of Transportation, Washington, USA.
Osterberg, J. O. (1998). The Osterberg load test method for bored and driven piles the first ten years. Proceedings of 7th International Conference & Exhibition on Piling and Deep Foundations, pp. 1-17, Vienna, Austria.
Randolph, M. F.; Wroth, C. P. (1978). Analysis of deformation of vertically loaded piles. Journal of the Geotechnical Engineering Division, vol. 104, nº 12, pp. 1465-1487.
Riccomini C.; Coimbra A.M. (1992). Geologia da Bacia Sedimentar. Mesa Redonda – Solos da cidade de São Paulo, ABMS/ABEF, pp. 37-94, São Paulo, Brasil.
Seo, H.; Moghaddam, R. B.; Lawson, W. D. (2016). Assessment of methods for construction of an equivalent top loading curve from O-cell test data. Soils and Foundations, vol. 56, nº 5, pp. 889-903.
Silva, P. E. C. A. F. (1983). Célula Expansiva Hidrodinâmica: Uma nova maneira de executar provas de carga. Publicação independente, Belo Horizonte, Brasil, 106p.
Silva, P. E. C. A. F. (1986). Célula Expansiva Hidrodinâmica: Uma nova maneira de executar provas de carga. Anais do 8º Congresso Brasileiro de Mecânica dos Solos e Engenharia de Fundações – COBRAMSEF, vol. 6, pp. 223-241, Porto Alegre, Brasil.
