| 摘要 |
PROBLEM TO BE SOLVED: To eliminate a phenomenon in which a manhole conduit is lifted by high-pressure groundwater when an earthquake that is so strong as causing liquefaction of the ground, occurs, and to provide an easy and effective technique of preventing lifting of the manhole conduit, because there is not such an easy and effective technique among conventional ones. SOLUTION: The manhole conduit is buried in the ground from above the ground surface by assuming a downward facing position. A manhole conduit trunk section 11 has a number of water guiding recessed grooves 16 extending in the vertical direction, formed in a peripheral surface thereof at circumferential intervals. Therefore when an earthquake that is so strong as causing liquefaction of the ground, occurs, the high-pressure groundwater is quickly released to a place from which a manhole conduit lifting force is not applied, via the recessed grooves 16 formed in the peripheral surface of the manhole conduit trunk portion. COPYRIGHT: (C)2007,JPO&INPIT
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