| 摘要 |
PROBLEM TO BE SOLVED: To provide a structurally improved pit cover which has high strength and for which little metallic raw material is used. SOLUTION: In this underground or underwater structure, particularly, the structurally improved pit cover, a pit cover body is composed of some first metallic pipes which are horizontally juxtaposed and fixedly connected together, and the whole of the inside of the first metallic pipe is filled with concrete. The pit cover body includes the plurality of first metallic pipes and the concrete; little metallic raw material is used for the plurality of first metallic pipes; costs are low; and since the concrete is infilled into the plurality of first metallic pipes, strength is proper, and the shear strength of the metallic pipe is high. Even if a thief steals the pit cover, he/she cannot steal the metallic raw material because the metallic raw material is very hard to take out. Additionally, the first metallic pipe may be formed as a square pipe, and may also be formed as a circular pipe. COPYRIGHT: (C)2006,JPO&NCIPI
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