| 摘要 |
PROBLEM TO BE SOLVED: To mount a step to a concrete product with a vertically extending space inside, without providing a through-hole. SOLUTION: When manufacturing a body 1 of a manhole which is the concrete product with the vertically extending space inside, internal thread members 1 having holes opened to the space is embedded to permit comings and goings in the space of the body 1. After the manufacture of the body 1 is completed, external thread parts 311 provided at the step 3 are screwed to the internal thread members 2 to mount the step 3. COPYRIGHT: (C)2007,JPO&INPIT
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