Failure probability of helical foundation piles of transmission towers
DOI:
https://doi.org/10.24849/j.geot.2017.139.02Keywords:
Transmission lines, Foundations, Helical pilesAbstract
In the transmission line projects there are countless amounts of variability due to the fact that the transmission line consists on a work that can be extended by a few quilometers, going through a variety of geological units and different microclimates. The geological unit changes cause variability of the ground strength and microclimates changes insert variability in the actions. This way, the work assess the failure probability and security of a patch from LT high voltage 230 kV performed mostly with the type guyed towers and foundations in helical piles. The calculation of the loading on the towers was done by the software Tower considering the wind maps of the region. Resistances were determined based on the torque installation of piles, calibrated from pullout tests. The failure probability was obtained and the safety coefficients showed that when the helical piles are performed with reference to the installation design torque the failure probability is practically nil; however, when taking as reference the minimum installation depth defined in the project, the failure probability increases considerably.
Downloads
References
Alonso, U. R. (1991). Previsão e controle das fundações. Editora Edgar Blucher, São Paulo.
Ang, A. H. S. e Tang, W. (1984). Probability concepts in engineering planning and design. Volume II: Decision, risk and reliability. John Wiley and sons. New York, EUA.
Aoki, N.; Cintra, J. C. A.; Esquivel, E. R. e Russo Neto, L. (2008). Prediction of the Behaviour of a Pile Foundation Under Static Loading Condition Using In Situ Tests Results. Behaviour of CFA, Driven and Bored Piles in Residual Soil. Experimental Site - ISC'2 International Prediction Event., v. 1. p. 445-465.
Associação Brasileira de Normas Técnicas – “NBR-5422 (1985): Projeto de linhas aéreas de transmissão de energia elétrica”, Rio de Janeiro, ABNT.
Cardoso, A. S. e Fernandes, M. M. (2001). Characteristic values of ground parameters and probability of failure in design according of Eurocode 7. Géotechnique 51, No. 6, pp. 519- 531.
Carvalho, I. P. G. (2007). Estudo teórico-experimental da capacidade de carga à tração e compressão de estacas metálicas helicoidais. Tese (Mestrado em Engenharia) – Universidade Federal de Minas Gerais, Belo Horizonte.
Chance, A. B. (1994). Helical pier foundation systems. Technical Manual. 10p.
Chin, F. K. (1970). Estimation of the ultimate load of piles not carried to failure. Proceedings of the 2nd Southeast Asian Conference on Soil Engineering, pp. 81-90.
Das, B. M. (1990). Earth Anchors. Elsevier Science Publisher, New York.
Fellenius, B. H. (1975). Test load of piles and new proof test procedure. Journal of Geotechnical Engineering Division. ASCE, vol. 101, GT9, pp. 855-869.
Fellenius, B. H. (1980). The analysis of results from routine pile load tests. Ground Engineering, London, vol. 13, n.6, pp. 19-31.
Fusco, P. B. (1977). Fundamentos estatísticos da segurança das estruturas. Editora da Universidade de São Paulo e Ed. McGraw-Hill do Brasil.
Hoyt, R. M. e Clemence, S.P. (1989). Uplift capacity of helical anchors in soil. Proceedings of the 12th International Conference on Soil Mechanics and Foundation Engineering, vol. 2, pp. 1019-1022, Rio de Janeiro.
Mitsch, M. P. e Clemence, S. P. (1985). The uplift capacity of helix anchors in sand. Uplift behavior of anchor foundations in soil, Proceedings of a session sponsored by the geotechnical Engineering Division of the American Society of Civil Engineers in conjunction with the ASCE Convention in Detroit, Michigan, pp. 26-47.
Navajas, S. e Niyama, S. (1996). Ensaio de carregamento dinâmico em estacas moldadas in loco numa obra portuária. Terceiro seminário de Engenharia de Fundações Especiais e Geotecnia: São Paulo, vol 1, pp. 331-342.
Perko, H. A. e Rupiper, S. J. (2000). Energy method for predicting installation torque of helical foundations and anchors. Proceedings of GeoDenver. Geotechnical Special Publication, ASCE, Reston, VA.
Perko, H. A. (2009). Helical piles: a practical guide to design and installation. John Wiley & Sons, USA.
Stephenson, R. W (2003). Design and installation of torque anchors for tiebacks and foundations. University of Missouri-Rolla;
Terzaghi, K. (1942). Pile-driving formulas. Discussion on the progress report of the committee on the bearing value of pile foundations. Proceedings of the ASCE, v. 68, n. 2, pp. 311-323, Feb.
Velloso A. D e Lopes R. F. (2009). Fundações. Oficina de Textos, São Paulo.
