PROBLEM TO BE SOLVED: To securely cut off water from the joint of a box culvert even when the spaces between joints are expanded because of an earthquake or the like.;SOLUTION: An endless-shaped outer projection 36 is provided on the end surface 12 of one box culvert 2a. Then an endless-shaped inner projection 16, which is internally engaged with the outer projection 36, is provided on the end surface 14 of the other box culvert 2b. A water stop material 50, which is attached to the projection of either the inner projection 16 or the outer projection 36, is constituted by an embedded part 52 and a compressed part 54, and the boundary parts 56 are mutually strung in a constricted state. Then an inner elastic layer 58 made of elastic solid rubber and an outer hard layer 60 made of hard solid rubber are provided to the compressed part 54. The embedded part 52 is embedded in one projection 16 beforehand, and the compressed part 54 is brought into friction contact with the other projection 36. Thus, the compressed part 54 is pulled to the base end side of the one projection 16, and the compressed part 54 is compressed by being sandwitched between the outer peripheral surface 30 of the inner projection 16 and the inner peripheral surface 38 of the outer projection 36.;COPYRIGHT: (C)2008,JPO&INPIT
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