| 摘要 |
PROBLEM TO BE SOLVED: To provide various items with a slip preventing effect more higher than a conventional sliding preventing surface structure, a mat, a subgrade bed or the like, and providing limit performance even when vehicle traffic is large, and a surface is worn. SOLUTION: A recessed part 2 is provided on a top face of a manhole lid body 1 made of casting, around a basic protruding part 3 provided in a V-shaped groove 4, a plurality of unit protruding part groups wherein another plurality of basic protruding parts 3 is arranged in positions at anglesθon a circumference of a radius L such that directions of grooves 4 of the basic protruding parts 3 are mutually different, is arranged on the recessed part 2, and a basic protruding part is provided to fill a gap formed between each unit protruding part group. COPYRIGHT: (C)2009,JPO&INPIT
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