Application of Brillouin Scattering-Based Distributed Optical Fiber Strain Sensor to Actual Concrete Piles

Hiroshige OHNO  Hiroshi NARUSE  Toshio KURASHIMA  Atsushi NOBIKI  Yasuomi UCHIYAMA  Yuki KUSAKABE  

IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.4   pp.945-951
Publication Date: 2002/04/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Optical Fibers and Devices)
optical fiber sensor,  strain,  Brillouin scattering,  concrete pile,  on-site-pouring,  load testing,  

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We applied a Brillouin-OTDR, which is a distributed optical fiber strain sensor, to two actual concrete piles. The piles were made for use as highway foundations by on-site-pouring at construction sites and underwent load testing to ensure that their characteristics satisfied the required levels. Compressive strain caused by the load exerted on the piles was measured to an accuracy of 0.01% and a spatial resolution of 1 m. This measurement was obtained by embedding a strain-sensing optical fiber in the piles during construction. The results showed that there was good agreement between the measured strain and both the theoretical values and the values obtained with a conventional strain gauge based on electric resistance. Furthermore, the obtained strain distribution reflected the effects of friction between the pile surface and the ground. These results demonstrate the effectiveness of the Brillouin-OTDR for this kind of testing and also as a means of obtaining detailed data on the strain in concrete piles.