| 摘要 |
PROBLEM TO BE SOLVED: To provide a strain and displacement sensor utilizing optical fibers, which is easy in assembling and installation, superior in handleability, is hardly subjected to the length restriction, and stable in performance. SOLUTION: An object under monitoring such as ground is bored, a pipe 1 is inserted in the bore down to a desired depth for observation, a U-shape folded optical fiber cable 2 is inserted in the pipe 1, a coagulant 3 such as concrete is poured into it to integrate the optical fiber cable 2 with the pipe 1, and the strain occurring in optical fibers of the cable is measured. Cleats 4 are preferably provided in the pipe 1 for fixing the optical fiber cable 2 to the cleats, and a weight 5 is preferably attached to the fold back point of the cable 2, so that the cable 2 can be inserted smoothly in the pipe 1 owing to the natural fall of the weight.
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