| 摘要 |
PROBLEM TO BE SOLVED: To make it easy to fix an optical fiber for strain measurement to a wall surface. SOLUTION: In a fixation groove Tm formed in the internal wall surface Ta of the tunnel T, many optical fiber fixing jigs 1 are fitted and fixed at specific intervals, and into the insertion holes 2g of those jigs 1, one optical fiber F is inserted from a guide-in groove 2h and fixed in a tensed state while preferably applied with a tensile force for 0.2 to 0.3% straining (extension). In this case, the guide-in groove 2h is open in the front surface 2c of a block body 2, so the optical fiber F can easily and skillfully be inserted into the insertion holes 2g. |
