東京都心部を縦断する大深度•長距離シールドの設計:東京下水道千代田幹線

摘要

As sewerage system in Tokyo has been in place for approximately 130 years since sewer was first built in Kanda, The Tokyo Metropolitan Government Bureau of Sewerage is rebuilding sewerage infrastructure. Reconstruction due to deterioration is particularly necessary for the Iidabashi, Chudan and Koudan sewers main that flow through Tokyo but as their average water level are high and it is difficult to reconstruct, we made a project is to build the Chiyoda sewer main which is alternatively used as those existing sewer pipes in order to reduce the water level of them to allow to conduct reconstruction. The Chiyoda sewer main Project consists of the laying of an 8.7km pipe from near JR Iidabashi Station to Tokyo Metropolitan Government Bureau of Sewerage Shibaura Water Regeneration Plant using a shield TBM with an outer diameter of 5.5m (inner diameter: 4.9m) which drills under approximately 50m. It is one of the largest project in the Bureau of Sewerage. This report contains information on issues investigated during design (original design).%東京下水道は，神田下水の整備から約130年が経過しており再構築を進めている.都心部を流れる飯田橋幹線，中段幹線，高段幹線などは，老朽化が著しく再構築が必要であるが，平常水位が高く再構築工事を行うことが困難なため，代替幹線である千代田幹線を整備し，既設幹線の水位を低下させ，再構築工事を行う計画である 千代田幹線整備事業は，JR飯田橋駅近傍から，東京都下水道局芝浦水再生センターまでの延長約8.7kmの幹線を，シールド外径5.5m(内径4.9m)， 土かぶり約50mで布設するものであり，東京下水道における幹線整備事業の中でも最大級の巨大プロジェクトである 本稿では，その設計(当初計画）において検討した課題などについて報告する.