| 摘要 |
PROBLEM TO BE SOLVED: To provide a blocking plate (inner lid) capable of preventing a third party from intruding into a handhole for a pipe passage buried into the ground, saving labor by reexamining a structure, and obtaining the structure preventing an inner empty cross section in a pit entering part of the handhole from being contracted as much as possible to allow only an owner to open and close it. SOLUTION: The blocking plate (the inner lid) attachable without providing a receiving frame (supporting frame) on the inner face of the pit entering part of the handhole to prevent the third party from intruding into the handhole and allow only the owner to open and close it is provided to reduce cost, shorten a construction period, and improve the workability of maintenance and inspection work. COPYRIGHT: (C)2008,JPO&INPIT
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