| 摘要 |
PROBLEM TO BE SOLVED: To measure deformation such as the torsion of an immersed tube, particularly a large-sized one having length of 100 m constituting an immersed tunnel accurately and easily at the time of manufacture, at the time of immersion, after immersion, etc., for reflection to construction management, etc. SOLUTION: Optical fiber cables 1, 1... are made to creep on the outer circumferential surface of a tube body 10, and installed along the four sides ab, be, cd, da and diagonal two sides ac, bd of a measuring surface. The optical fiber cables 1, 1... for measurement and for temperature correctuon, etc., are mounted in parallel while pairing two, and both sides of the optical fiber cables 1 for measurement are fixed onto the tube body 10 under a tensed state. The elongation of the optical fiber cables 1, 1... is measured by the detection of Brillouin scattering, and the deformation of the whole tube body 10 is measured by the difference of the elongation of the optical fiber cables 1 for measurement and the optical fiber cables 1 for temperature correction, etc.
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