| 摘要 |
PROBLEM TO BE SOLVED: To provide a manhole and a soil chamber cover structure, capable of releasing toxic and explosive gas in a soil chamber by an air vent of a steel cover of the manhole and the soil chamber, and capable of preventing infiltration of rainwater, . SOLUTION: One or more air vents 100 are arranged in the steel cover 10 of the manhole and the soil chamber. Ventilation port packing 103 is arranged in the air vent 100. The air vent can be blocked up by a packing body 151 when the rainwater intrudes via the ventilation port packing 103, and can be opened by the packing body 151 when the rainwater does not intrude. COPYRIGHT: (C)2005,JPO&NCIPI
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