A V block method is a new construction technique for connecting a final part of immersed tunnel. A characteristic of this method is hydrauric coupling with a wedge block. Adopting the V block method makes possible to reduce underwater works greatly. Consequently, reliability and safety of the constructions at deep-water are improved. The Third Port construction Bureau, Ministry of Transport, adopted the new method for the first time in the world at the Osakako-Sakishima Tunnel.

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