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Tokyo Port Daiichikoro Tunnel
(Rinkai Tunnel)
Tokyo Port Tunnel
Tunnel Rehabilitation
  Tokyo Port Daiichikoro Tunnel
(Rinkai Tunnel)

The Tokyo Port Daiichikoro tunnel (Rinkai Tunnel) is a reinforced concrete immersed-tube tunnel constructed in soft ground under Tokyo Bay. The tunnel is of enormous scale and was completed in 2001. With a length of 1,329 m, total immersed tube width of 32.3 m, and height of 10 m, it carries four lanes of traffic in both directions. The tunnel sections were pre-cast and barged into position before being emplaced in an excavated trench in water where the depth to the natural seabed was 29 m. The trench was then backfilled to provide 2.0 m of cover over the tunnel. The tunnel is formed from eleven reinforced concrete tube sections.

Role of NCC in tunnel construction
The Tokyo Port Daiichikoro Tunnel is one of six immersed tube tunnels that NCC has designed in Japan. A typical technical challenge for the design of such tunnels is providing earthquake resistant construction, especially given that the immersed tube is embedded within thick deposits of soft sediments which can easily liquefy during an earthquake. NCC spent three years undertaking experimental investigations to develop a more flexible joint. As a result, three types of rubber gaskets were developed for use in this and subsequent tunnels. The joints formed with these gaskets would enable the tube structure to withstand deformations from an earthquake of the magnitude of the Great Hanshin earthquake that devastated the city of Kobe in 1995.
Immersed tube tunnel construction

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