| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a fire resistant structure for backfill injection hole in which construction is simplified, work such as check or repair is facilitated and a cut-off performance and fire resistance can surely be secured, and a method of forming the fire resistant structure for the backfill injection hole. <P>SOLUTION: In a backfill injection hole 3 formed in a tunnel segment 1 installed along a wall surface of a natural ground 13, a check valve 19 is installed at a predetermined interval from the natural ground 13, and a space between the check valve 19 and the natural ground 13 is filled with a back filler 51. Next, at a predetermined interval in a tunnel internal vacant direction from the check valve 19, a steel cock 23 is installed which includes a lock portion corresponding to the backfill injection hole 3, a cover portion capable of closing the backfill injection hole 3 and a cock protector lock portion provided in the cover portion. Thereafter, at a tunnel internal vacant side of the cock 23, a ceramics cock protector 27 is installed which has a recess as a lock portion corresponding to the cock 23. The cock protector 27 closes a diameter-expanded portion 11b of the backfill injection hole 3 as a whole. <P>COPYRIGHT: (C)2012,JPO&INPIT |
