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31 May 1999 Fiber optic Bragg grating sensors embedded in GFRP rockbolts
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Rockbolt anchors for tunnel or mine roofs are key elements during construction and operation. We report on the fabrication of glass fiber reinforced polymer (GFRP) rockbolts with embedded fiber optical Bragg grating sensors and their first field application in a test tunnel. Optical fibers and in-fiber Bragg grating sensors were embedded in GFRP rockbolts during a continuously ongoing pultrusion process on an industrial production machine. Depending on their outer diameter the rods equipped with fiber sensors serve as measuring rockbolts or as extensometric sensors for the motion of boulders in the tunnel roof. The adhesion and force transfer of different fiber coatings were tested by push-out experiments. By temperature and strain cycle tests the performance of the rockbolt sensors was evaluated. We will present these results and the measurements made during a first installation of fiber optical rockbolt sensors in a tunnel.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Andreas Frank, Philipp M. Nellen, Rolf Broennimann, and Urs J. Sennhauser "Fiber optic Bragg grating sensors embedded in GFRP rockbolts", Proc. SPIE 3670, Smart Structures and Materials 1999: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials, (31 May 1999);

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