ABSTRACT
The New Tomei-Meishin expressway is a high-speed highway facility having six lanes (three lanes for each direction) throughout its total length of 502km. The expressway is planned to form a new transportation backbone for Japan in the 21st Century by connecting between Tokyo and Kobe. This expressway is functioning as a supplemental expressway of the existing Tomei and Meishin expressways. The tunnels on the New Tomei-Meishin expressway have a very large, flattened cross-section of approximately 190m2 excavation area, while the excavation width is approximately 18m. There is no previous example of a large number of tunnels having a huge cross-section in the world, which can be used as references. Thus, there are various problems appearing regarding to determine the technical configuration and support structure, in terms of construction such as how to excavate a large group of tunnels safely and efficiently. The study and investigation related to design and construction method for the large cross-section tunnels located in various ground conditions is described in this paper.
