SEIKAN UNDERSEA TUNNEL TO LINK HONSHIE AND HOKKAIDO
Kentaro Hama · 1972
This article gives an account of the construction of the Seikan Tunnel which is being built beneath the Tsugaru Strait to link the two Japanese Islands, after outlining the general plan of this rail link, the author gives details of the preliminary investigations that were made by mapping and geological investigations which included dredging, seismic, sonic and magnetic prospecting, and the drilling of boreholes. Details are given of the extensive pilot tunnelling that was carried out in advance of the main tunnelling. The author describes the excavation of the included tunnels that lead down to the main tunnel beneath the Strait, and includes details of the problems that were encountered in the various geological formations and the boring of pilot-holes in advance of the tunnels. Details are also given of the water that was found and of the grouting methods that were employed to seal the excavations from the ingress of water. The article is concluded by a brief account of the progress that has been made with the main tunnel under the Strait, which is scheduled to be completed in 1979. /TRRL/