It is difficult to mention Japan at the moment without including the 2011 Tohoku earthquake and its effects. The obvious destruction and effect it has had across all industries and interests, not least the environment. Even the special committee for studying seismic damage to tunnels has had its efforts hindered.

Following the crisis, the Japanese Ministry of Economy, Trade and Industry indicated that the production output index of factories and mines in the country stands at 82.7 (with the base of 100 set at 2005 levels). The record drop of production in March, 15.5 per cent, is not a surprise given the circumstances but shows the level of impact that might be expected across the board. The Japanese economy is in its third recession in 10 years.

The JTA’s pick of the projects
Although the damage to tunnels in Japan has yet to be gathered in full, and projects under construction are particularly at risk (see article on page 32), the health of the industry and amount of work available is undeniable. A lot of this work is on the Metropolitan Expressways in the Greater Tokyo Area. Contractors Kajima, Taisei, Obayashi and Hazama are handling Shinagawa Tunnel on the Central Circular Route, while Obayashi and Shimizu are working on the Northern Tunnel on the Yokohama Circular Route. Aside from these, there is also work on the Hokkaido and West Kyushu Shinkansen (Bullet Train) lines, the new Tokyo-Nagoya Expressway and also the Horobetsu Radioactive Waste Research Facility, according to Toshinori Mizutani, executive director of the JTA.

The JTA is publishing a book to include the rest of the world in its activities. ‘Tunnelling Activities in Japan, 2010’ is available for JPY 3,600 (USD 44.16) from the JTA website. The book has a juicy range of topics, including a look at tunnelling in geological formations characterised by extreme swelling tendencies with a high-pressure aquifer, recent technological innovations and several interesting projects that have been underway in Japan.

Key project: Trans-Tokyo Bay
At 14.14m, the Hitachi Zosen slurry shield TBM working on the Kawasaki tunnel Ukishima-North phase one section of the project is one of the largest in the world. The completed tunnel will have an internal diameter of 11.9m and a grade of four per cent and a horizontal curve with a radius of 1600m. The project client, the Trans-Tokyo Bay Highway Corporation, awarded the contract to a JV of Kumagai Gumi, Hazama and JDC. The overall project involves the construction of artificial islands.

Special report
In this special report on North East Asia you will find an article discussing what is known and can be expected from seismic damage assessments in Japan. T&TI speaks to the chair of the damage study committee, Toshihiro Asakura, to bring you the latest approaches, and past studies into the mechanics of seismic tunnel damage.

On page 37 Hee Soon Shin of the Korea Institute of Geoscience & Mineral Resources gives a paper on the Use of Underground Space in Korea. The article reviews underground projects in Korea, including refrigerated food storage, oil and gas storage, pumped storage, road, metro and rail tunnelling projects.