Distributed Fiber Optic Sensing of Axially Loaded Bored Piles
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 144, Issue 3
Abstract
Instrumented pile tests are vital to establish the performance of a pile and validate the assumptions made during initial design. Conventional instrumentation includes vibrating wire strain gauges and extensometers to measure the change in strain or displacements within a pile. Although these strain and displacement gauges are very accurate, they only provide strain/displacement readings at discrete locations at which they are installed. It is therefore common to interpolate between two consecutive points to obtain values corresponding to the data gaps between points; in practice, these discrete instrumented points could be tens of meters apart, at depths corresponding to different soil layers, and hence simple interpolation between the measurement points remains questionable. The Brillouin optical time-domain reflectometry fiber optic strain sensing system is able to provide distributed strain sensing along the entire length of the cable, enabling the full strain profile to be measured during a maintained pile load test. The strain data can also be integrated to obtain the displacement profile. This paper presents three case studies which investigate the performance of three concrete bored piles in London using both conventional vibrating wire strain gauges and distributed fiber optic strain sensing during maintained pile load tests, which enable comparisons made between the two instrumentation systems. In addition, finite-element analyses show that the ability to measure the full strain profiles for each pile is highly advantageous in understanding the performance of the pile and in detecting any abnormalities in the pile behavior.
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Acknowledgments
This research was conducted within the Centre for Smart Infrastructure and Construction (CSIC) of the University of Cambridge, funded by EPSRC and Innovate U.K. Their financial assistance is gratefully acknowledged. The assistance of the CSIC team is acknowledged, including Professor Lord Robert Mair, Dr. Jennifer Schooling, Peter Knott, Jason Shardelow, and Jules Birks. Finally, the authors acknowledge the contribution of the numerous CSIC Industry partners, especially ARUP (Duncan Nicholson, Paul Morrison, and Stuart Pennington), Cementation Skanska (Andrew Bell, Martin Pedley, and Rab Fernie), and Laing O’Rourke.
References
Abchir, Z., Burlon, S., Frank, R., Habert, J., and Legrand, S. (2016). “t-z curves for piles from pressuremeter test results.” Géotechnique, 66(2), 137–148.
Acikgoz, M. S., Pelecanos, L., Giardina, G., Aitken, J., and Soga, K. (2017). “Distributed sensing of a masonry vault during nearby piling.” Struct. Control Health Monitor., 24(3), e1872.
Acikgoz, M. S., Pelecanos, L., Giardina, G., and Soga, K. (2016). “Field monitoring of piling effects on a nearby masonry vault using distributed sensing.” Int. Conf. of Smart Infrastructure and Construction, ICE Publishing, Cambridge, U.K.
API (American Petroleum Institute). (2002). “Planning, designing and constructing fixed offshore platforms—Working stress design.” API RP 2A-WSD, Washington, DC.
Bathe, K. J. (1996). Finite element procedures, 1st Ed., Prentice Hall, Englewood Cliffs, NJ.
Berezantzev, V. G., Khristoforov, V. S., and Golubkov, V. N. (1961). “Load bearing capacity and deformation of piled foundations.” Proc., 5th Int. Conf. on Soil Mechanics and Foundation Engineering, Paris.
British Standards Institution. (1995). “Part 1: General rules (together with United Kingdom national application document).” Eurocode 7, London.
Bustamante, M., and Gianeselli, L. (1982). “Pile bearing capacity predictions by means of static.” Proc., 2nd European Symp. on Penetration Testing, Amsterdam, Netherlands.
Butterfield, R., and Banergee, P. K. (1971). “The elastic analysis of compressible piles and pile groups.” Geotechnique, 21(1), 43–60.
Cheung, L., Soga, K., Bennett, P. J., Kobayashi, Y., Amatya, B., and Wright, P. (2010). “Optical fibre strain measurement for tunnel lining monitoring.” Proc. ICE Geotech. Eng., 163(3), 119–130.
Comodromos, E. M., and Bareka, S. V. (2009). “Response evaluation of axially loaded fixed-head pile groups in clayey soils.” Int. J. Numer. Anal. Methods Geomech., 33(17), 1839–1865.
de Battista, N., Elshafie, M. Z. E. B., Soga, K., Williamson, M., Hazelden, G., and Hsu, Y. S. (2015). “Strain monitoring using embedded distributed fibre optic sensors in a sprayed concrete tunnel lining during the excavation of cross-passages.” 7th Int. Conf. on Structural Health Monitoring and Intelligent Infrastructure, London.
de Battista, N., Kechavarzi, C., Seo, H., Soga, K., and Pennington, S. (2016). “Distributed fibre optic sensors for measuring strain and temperature of cast-in-situ concrete test piles.” Proc., Int. Conf. on Smart Infrastructure and Construction, Thomas Telford, Cambridge, U.K.
Di Murro, V., Pelecanos, L., Soga, K., Kechavarzi, C., Morton, R. F., and Scibile, L. (2016). “Distributed fibre optic long-term monitoring of concrete-lined tunnel section TT10 at CERN.” Int. Conf. of Smart Infrastructure and Construction, ICE Publishing, Cambridge, U.K.
Doherty, P., et al. (2015). “Field validation of fibre Bragg grating sensors for measuring strain on driven steel piles.” Géotechnique Lett., 5(2), 74–79.
Eslami, A., and Fellenius, B. H. (1997). “Pile capacity by direct CPT and CPTU methods applied to 102 case histories.” Can. Geotech. J., 34(6), 886–904.
Fellenius, B. H. (1989). “Prediction of pile capacity.” ASCE Symp. on Predicted and Observed Behavior of Piles, London.
Frank, R., and Zhao, S. R. (1982). “Estimating the settlement of axially loaded bored piles in fine sand by PMT data.” Bull. Liaison LPC, 119.
Goldfeld, Y., and Klar, A. (2013). “Damage identification in reinforced concrete beams using spatially distributed strain measurements.” J. Struct. Eng., 04013013-11.
Hauswirth, D., Puzrin, A. M., Carrera, A., Standing, J. R., and Wan, M. S. P. (2014). “Use of fibre-optic sensors for simple assessment of ground surface displacements during tunnelling.” Geotechnique, 64(10), 837–842.
Horiguchi, T., Shimizu, K., Kurashima, T., Tateda, M., and Koyamada, Y. (1995). “Development of a distributed sensing technique using Brillouin scattering.” J. Light-Wave Technol., 13(7), 1296–1302.
Iten, M. (2011). “Novel applications of distributed fiber-optic sensing in geotechnical engineering.” Ph.D. thesis, ETH, Zurich, Switzerland.
Jardine, R. J., and Chow, F. C. (1996). New design methods for offshore piles, Marine Technology Directorate, London.
Kechavarzi, C., Soga, K., de Battista, N., Pelecanos, L., Elshafie, M. Z. E. B., and Mair, R. J. (2016). Distributed fibre optic strain sensing for monitoring civil infrastructure, Thomas Telford, London.
Kersey, A. D., and Morey, W. W. (1993). “Multiplexed Bragg grating fibre-laser strain-sensor system with mode-locked interrogation.” Electron. Lett, 29(1), 112–114.
Kitiyodom, P., and Matsumoto, T. (2003). “A simplified analysis method for piled raft foundations in non-homogeneous soils.” Int. J. Numer. Anal. Methods Geomech., 27(2), 85–109.
Klar, A., et al. (2006). “Distributed strain measurement for pile foundations.” Proc. ICE Geotech. Eng., 159(3), 135–144.
Klar, A., Dromy, I., and Linker, R. (2014). “Monitoring tunneling induced ground displacements using distributed fiber-optic sensing.” Tunnell. Underground Space Technol., 40, 141–150.
Knappett, J. A., and Craig, R. F. (2012). Craig’s soil mechanics, 8th Ed., CRC Press, London.
Kraft, M. L., Ray, R. P., and Kakaaki, T. (1981). “Theoretical t-z curves.” J. Geotech. Eng. Div., 107(11), 1543–1561.
Kulhawy, F. H., and Prakoso, W. A. (1999). “Discussion of end bearing capacity of drilled shafts in rock.” J. Geotech. Eng., 1106–1110.
Kurashima, T., Horiguchi, T., Izumita, H., and Tateda, M. (1993). “Brillouin optical-fiber time domain reflectometry.” IEICE Trans. Cummun., E76-B(4), 382–390.
Lee, C. Y. (1993). “Pile group settlement analysis by hybrid layer approach.” J. Geotech. Eng. Div., 984–997.
Lee, W., Lee, W., Lee, S., and Salgado, R. (2004). “Measurement of pile load transfer using the fiber Bragg grating sensor system.” Can. Geotech. J., 41(6), 1222–1232.
Lehane, B. M., Jardine, R. J., Bond, A. J., and Frank, R. (1993). “Mechanisms of shaft friction in sand from instrumented pile tests.” J. Geotech. Eng., 19–35.
Levenberg, K. (1944). “A method for the solution of certain non-linear problems in least squares.” Q. Appl. Math., 2(2), 164–168.
Linker, R., and Klar, A. (2017). “Detection of sinkhole formation by strain profile measurements using BOTDR: Simulation study.” J. Eng. Mech., B4015002.
Liu, J., and Zhang, M. (2012). “Measurement of residual force locked in open-ended pipe pile using FBG-based sensors.” Electron. J. Geotech. Eng., 17, 2145–2154.
Marduardt, D. (1963). “An algorithm for least-squares estimation of nonlinear parameters.” SIAM J. Appl. Math., 11(2), 431–441.
McCabe, B. A., and Lehane, B. M. (2006). “Behavior of axially loaded pile groups driven in clayey silt.” J. Geotech. Geoenviron. Eng., 401–410.
Ménard, L. (1963). “Calcul de la force portante des fondations à partir des essais pressiométriques.” Sols-Soils, 6, 9–27 (in French).
Meyerhof, G. G. (1965). “Shallow foundations.” J. Soil Mech. Found. Div., 91(2), 21–31.
Mohamad, H. (2007). “Distributed optical fibre strain sensing of geotechnical structures.” Ph.D. thesis, Univ. of Cambridge, Cambridge, U.K.
Mohamad, H., Bennett, P. J., Soga, K., Mair, R. J., and Bowers, K. (2010). “Behaviour of an old masonry tunnel due to tunnelling-induced ground settlement.” Geotechnique, 60(12), 927–938.
Mohamad, H., Soga, K., Bennett, P. J., Mair, R. J., and Lim, C. S. (2012). “Monitoring twin tunnel interaction using distributed optical fiber strain measurements.” J. Geotech. Geoenviron. Eng., 957–967.
Mohamad, H., Soga, K., Pellew, A., and Bennett, P. J. (2011). “Performance monitoring of a secant-piled wall using distributed fiber optic strain sensing.” J. Geotech. Geoenviron. Eng., 1236–1243.
Osterberg, J. O., and Pepper, S. F. (1984). “A new simplified method for load testing drilled shafts.” Found. Drill., 23(6), 9–11.
Ouyang, Y., Broadbent, K., Bell, A., Pelecanos, L., and Soga, K. (2015). “The use of fibre optic instrumentation to monitor the O-Cell load test on a single working pile in London.” Proc., XVI European Conf. on Soil Mechanics and Geotechnical Engineering, London.
Pelecanos, L., et al. (2017). “Distributed fibre-optic monitoring of an Osterberg-cell pile test in London.” Geotech. Lett., 7(2), 1–9.
Pelecanos, L., and Soga, K. (2017). “Using distributed strain data to evaluate load-transfer curves for axially loaded piles.” J. Geotech. Geoenviron. Eng., in press.
Pelecanos, L., Soga, K., Hardy, S., Blair, A., and Carter, K. (2016). “Distributed fibre optic monitoring of tension piles under a basement excavation at the V&A museum in London.” Int. Conf. of Smart Infrastructure and Construction, ICE Publishing, Cambridge, U.K.
Poulos, H. G. (1989). “Pile behaviour—Theory and application.” Geotechnique, 39(3), 365–415.
Poulos, H. G., and Davis, E. H. (1974). Elastic solutions for soil and rock mechanics, Wiley, New York.
Randolph, M. F. (2003). “Science and empiricism in pile foundation design.” Geotechnique, 53(10), 847–875.
Salgado, R. (2008). The engineering of foundations, McGraw-Hill, New York.
Savitzky, A., and Golay, M. J. E. (1964). “Smoothing and differentiation of data by simplified least squares procedures.” Anal. Chem., 36(8), 1627–1639.
Schwamb, T., et al. (2014). “Fibre optic monitoring of a deep circular excavation.” Proc. ICE Geotech. Eng., 167(2), 144–154.
Schwamb, T., and Soga, K. (2015). “Numerical modelling of a deep circular excavation at Abbey Mills in London.” Geotechnique, 65(7), 604–619.
Seo, H.-J., Pelecanos, L., Kwon, Y.-S., and Lee, I. M. (2017). “Net load–displacement estimation in soil-nail pullout tests.” Proc. Inst. Civ. Eng. Geotech. Eng., 170(6), 1–14.
Soga, K. (2014). “Understanding the real performance of geotechnical structures using an innovative fibre optic distributed strain measurement technology.” Rivista Italiana di Geotechnica, 4, 7–48.
Soga, K., et al. (2015). “The role of distributed sensing in understanding the engineering performance of geotechnical structures.” Proc., XVI European Conf. on Soil Mechanics and Geotechnical Engineering, Thomas Telford, London.
Soga, K., et al. (2017). “Distributed fibre optic strain sensing for monitoring underground structures—Tunnels case studies.” Underground sensing, S. Pamukcu and L. Cheng, eds., 1st Ed., Elsevier, Amsterdam, Netherlands.
Stas, C. V., and Kulhawy, F. H. (1984). “Critical evaluation of design methods for foundation under axial uplift & compression loading.”, Electric Power Research Institute, Palo Alto, CA.
Tomlinson, M., and Woodward, J. (2014). Pile design and construction practice, CRC Press, New York.
Tomlinson, M. J. (1997). “The adhesion of piles driven in clay.” Proc., 4th Int. Conf. on Soil Mechanics and Foundation Engineering, London.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 144 • Issue 3 • March 2018
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©2017 American Society of Civil Engineers.
History
Received: Mar 7, 2016
Accepted: Sep 1, 2017
Published online: Dec 28, 2017
Published in print: Mar 1, 2018
Discussion open until: May 28, 2018
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