Abstract
This paper presents a case study of an Osterberg-cell test of a pile located at the Isle of Dogs in London, which was heavily instrumented with distributed optical-fibre sensors, strain gauges, displacement transducers and extensometers. Special emphasis is given on the data from fibre optics, which offers an advantage due to their spatially continuous nature. The data show a clear development of shaft friction with the applied load and also some unexpected pile–soil slip within two of the soil layers, which is attributed to the development of a filter cake due to the long construction time. Relevant finite-element analyses are also conducted in an attempt to further understand the mechanisms of pile–soil slip, which highlight its importance in predicting the vertical displacements. Finally, some comments are included on the observed behaviour of the founding chalk layer.
Highlights
Pile load tests are vital for understanding the actual field behaviour of piles and for determining the relevant geotechnical parameters (Lehane & Jardine, 1994; Seo et al, 2013; Bica et al, 2014)
This paper presents a case study of an Osterberg-cell (O-cell) pile test in London instrumented with distributed fibre optics (FOs) and other conventional instrumentation (VWSGs and extensometers)
The pile was monitored during both curing of the concrete and the O-cell test, the analysis and discussion in this paper focuses on the latter only
Summary
Pile load tests are vital for understanding the actual field behaviour of piles and for determining the relevant geotechnical parameters (Lehane & Jardine, 1994; Seo et al, 2013; Bica et al, 2014). Recent advances have made use of the interaction of laser pulses in fibre optics (FOs), through techniques such as fibre Bragg gratings (Kersey & Morey, 1993; Lee et al, 2004; Liu & Zhang, 2012; Doherty et al, 2015) and distributed Brillouin optical time-domain reflectometry (BOTDR) (Cheung et al, 2010; Mohamad et al, 2011; Hauswirth et al, 2014; Klar et al, 2014; Schwamb & Soga, 2015; Kechavarzi et al, 2016; Acikgoz et al, 2017) to obtain larger datasets The latter, due to their continuous nature, has a promising advantage over conventional, discrete instrumentation in providing detailed information about the pile performance (Klar et al, 2006; Ouyang et al, 2015). Two types of FO cables were installed: a reinforced Fujikura and an Excel Unitube measuring strain and temperature, respectively They were attached to the reinforcement cage prior to concrete casting and they were split into two regiments based on their point of termination: above the O-cell and to the pile bottom. The strain profiles within the chalk layer seem to be rather constant implying a small SF contribution from the chalk layer
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
