| 摘要 |
PROBLEM TO BE SOLVED: To provide the cleaning method for a sewerpipe which prevents an optical fiber from being damaged by jet water for cleaning, sewage, solid bodies, etc., in the sewerpipe which strike on the optical fiber. SOLUTION: The protection device which has a beltlike protection sheet 10 mounted between a support rod 11 and a tension device 12 by using wires 18 fitted both its edges is prepared; and the protection sheet 10 is inserted and arranged in the sewerpipe 20 to be cleaned and the support rod 11 and tension device 12 arranged in both the manholes 15 and 16 positioned on both the sides of the sewerpipe 20 respectively. The support rod 11 is engaged with the flank of the manhole 15 and in this state, the tension device 12 is placed in operation to draw the wire 18 and give specific tension, thereby making both the edges of the protection sheet 10 about against specific positions on the inside surface 20a of the sewerpipe 20. Consequently, the optical fiber 37 arranged in the sewerpipe 20 is covered. Even when the inside of the sewerpipe positioned in the lower space of the protection sheet 10 is cleaned in this state by using jet water, none of the jet water strikes on the optical fiber 37 because of the protection sheet 10. |
