Safety in quick construction of a long water conveyance channel by shield tunneling method

摘要

Kanto Regional Development Bureau, The Ministry of Land, Infrastructure and Transport has been implementing the Kasumigaura water conveyance project, which consists of the 42.6-km Naka Water Conveyance Channel between Lake Kasumigaura and the Naka River in Ibaraki Prefecture and a 2.6-km water conveyance channel connecting Lake Kasumigaura and the Tone River. The objectives are to let water flow through the Naka River, Lake Kasumigaura and the Tone River to improve water quality in Lake Kasumigaura and the Sakura River, stabilize water use based on the existing water rights in the Tone River and the lower Naka River, conserve river environments and ensure additional use of urban water. In the Kasumigaura water conveyance project, the new Ishioka Tunnel project (in the second work section) involves the construction of a water conveyance tunnel with an inner diameter of 3.5 m by the slurry shield tunneling method. The project has characteristics of long-distance excavation and quick construction. The tunnel has a length of 5000 m without any intermediate shafts. This is one of Japan's leading long-distance tunneling projects.