| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical fiber stretching system for observation of ground deformation capable of detecting ground deformation stably and at high precision for a long period. SOLUTION: Piles 11 are provided having an interval from each other to be fixed in ground 12 in an area subject to observation. A cable 20 is fixed in a tensed state to the pile 11 through a support mechanism 21, an optical fiber 2 is set in parallel to the cable 20 as a supporting body like a splint, and they are fixed by a clamp 35 as tension is applied. Distribution of length direction distortion in the optical fiber 2 is measured at one end of the optical fiber 2 by an optical fiber distortion analyzer. In this constitution, the optical fiber 2 is securely distorted in accordance with ground deformation, and by detecting its distortion, the ground deformation can be securely measured. Since the optical fiber 2 is reinforced with the cable 20, breakage or loosening will not be generated, thereby it can be stably used for a long period.
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