事務所の取り組み
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首都圏外郭放水路
Overview of Facilities
Tunnel
This is an "underground river" constructed to lead flood water flowing in from the Nakagawa, Kuramatsu, Ootoshi-Furutone Rivers and others to the Edogawa River.
"Underground River" that Runs a total Distance of 6.3 km at 50m below Ground
It is about 6.3 kilometers long (roughly the distance from Kasukabe city’s Kamikanasaki to Kobuchi), has an interior diameter of ten meters, and runs underground 50 meters below Route 16. Fifty meters underground is even deeper than the subway. The discharge channel was created this deep because its creation could potentially interfere with future use of the area, and because there was a risk that the land would eventually be divided up. In addition, because it would take time to acquire a site for the tunnel, it was deemed that constructing it underground would allow the project to achieve its goals more quickly and smoothly. The soil excavated to create the tunnel is also recycled to create levees in the Edogawa River.
Slurry Shield Machine
A shield machine is a machine that creates a tunnel as it digs through the ground. There is a face plate with cutter bits attached to the tip of the cylindrical steel shield machine.
This face plate rotates and scrapes the soil while pushing the machine forward. Behind the shield machine, blocks called “segments” are automatically assembled into a cylindrical shape, which then becomes the interior wall of the tunnel.All-out Recycling
Among the types of soil produced by excavation during construction work carried out using the slurry shield method, secondary soil of a finer grain size has so far been treated as industrial waste.
However, since such soil became recyclable according to the revision of the law in 1997 if necessary requirements are met, this project was approved as No.1 and No.2 of the Health and Welfare Minister certification on July 23, 1998 and was approved as No.3 on October 1 of the same year. Treated soil generated from this construction work is used to construct the Edogawa River Super Embankment.