Recent Topics on Tunnel Engineering in Japan

Based on the investigation results on the damages of some underground structures due to the severe Kobe Earthquake it concludes that the aseismicity of underground is far superior to that of aboveground structures. Therefore, at first, necessity to reconstruct strong cities especially by good use of underground space will be discussed. Then two non-circular shield-tunneling projects in Japan are discussed. The first is construction of the world's first shield driven double track subway tunnel of rectangular shape for the Kyoto Municipal Subway. This paper presents a report on the overall planning, the tests that were performed in the process of planning, and the results of driving. The second is the design of the Hirakata Tunnel, with three traffic lanes and shoulders on one side, which will be constructed as one of the tunnels for The New Meishin (Nagoya-Kobe) Expressways. This paper presents the feasibility study of the shield tunneling method, using the same design criteria as the non-circular, horseshoe section of mountain tunnel, to the equivalent section of the Hirakata Tunnel.