| 摘要 |
PROBLEM TO BE SOLVED: To newly provide a protection plate device capable of preventing any damages to the surface where falling water hits in a manhole, culvert or rain water main pipe. SOLUTION: This is a protective plate device for a falling surface of running water of the manhole, culvert and rain water main pipe by covering the surfaces of a bottom invert as falling and running water surface for the manhole, culvert or rain water main pipe and nearby wall surfaces by forming the shape matched to the respective surface thereby preventing damages by a pressure created by the falling and running water and, in addition, a projected pattern having a directionality to reduce the speed of running water is made on the protection plate thereby preventing any damage even to the downstream region.
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