| 摘要 |
PROBLEM TO BE SOLVED: To enlarge the catchment area of a catching part and to improve the outside water catchability in a facility comprising a catchment area for collecting the outside water bled out onto a pipe surface from the ground at the outside of the pipe buried in the ground, by forming the drainage part into the band shape with a mat member having the flexibility and water permeability. SOLUTION: Relating to a pipe body 4 such as a hydraulic iron pipe or the like which is mounted in a tunnel 1 digged in the ground through a timbering 2 and around which the concrete 3 is placed, a catching part 50, a drainage part 60, a connection pipe 8 and a by-pass 9 are mounted as an outside water pressure reducing equipment. The catching part 50 is formed into the band shape with a mat member having the water permeability, and comprises a core material and a filter. In a case when the concrete 3 is placed around the pipe body 4, the outside water fleeding from the ground onto an outer surface of the pipe body through the concrete 3 flows into the approximately triangular voids formed at both side edges of the catching part 50, then uniformly entered into the water permeable space of the catching part 50, and discharged to the external through the connection pipe 8 and the drainage part 60.
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