| 摘要 |
PROBLEM TO BE SOLVED: To prevent the settlement of the protection cover of a manhole due ground settlement by installing an overhanging beam provided together with the protection cover upward of the manhole and overhanging outwardly on the outer periphery end of a ring. SOLUTION: A protection cover 11 provided upward on the vertical pipe 13 of manhole formation is installed through a pedestal ring 10 comprising a short piece cylinder. A locking groove 102 capable of locking the protection cover 11 is provided on the upper face of a pedestal ring 10, and the vertical pipe 13 is inserted in the inner peripheral face of the pedestal ring 10 to block the upper end of the vertical pipe 13 by an inner cover 12. Furthermore, an overhanging beam 101 overhanging outward is provided on the outer peripheral end of the ring 10, adhered to ground 14, and arranged so that load applied on the protection cover 11 is received. In this case, the protection cover 11 is formed of cast iron, formed of a cylindrical cover body 111 and a cover 112, and the cover body 111 comprises the cylindrical body of a both-end opening. Thereby the settlement of the protection cover 11 is prevented to extend the overhanging beam 101 outward, and the inclination of the pedestal ring 10 and the protection cover 11 can be prevented.
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