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Behavior of Compressed Air-Masses in Deep Tunnels Which May Blow Off Manhole Covers

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In urban sewer pipe systems, the phenomenon that manhole covers are brown off happens when it rains heavily. This phenomenon is caused by flow and air-masses. In this study, we focused on behavior of air-masses in deep tunnels by hydraulic model experiment. We understood that firstly the air-masses, formed by the appearance of unsteady hydraulic bores, are trapped at the top of the deep tunnels when the water level reaches near the top of the deep tunnels. Secondary the air-masses move to manhole by hydraulic surging and so on. Finally the air-masses spurt into the air, then the water level in manholes moves hardly. Especially, if water level in manholes is near the manhole covers, the air-masses affect the water level and manhole cover. Through the experiment, we understood that installation of a system which can separate the water from the air-masses is necessary to prevent the phenomenon that manhole covers may be brown off,

Keywords: Air-masses; Deep Tunnels; Hydraulic model experiment

Document Type: Research Article


Publication date: 2010-01-01

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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