Abstract:

Building a new highway tunnel in the metropolitan area is generally limited by the dense residential area, where the land acquirement is difficult, therefore the distance between the tunnel tubes has to be reduced, which derives the triplearch closelyspaced tunnel. In this article, the design of the excavation and support method of triplearch closelyspaced tunnel is investigated, with the newlybuilt triplearch closelyspaced tunnel in Xindian District, New Taipei, Taiwan as an example. The geological material of the tunnel in this case is weak, which leads to the lacking of the strength of the middle pillar after the excavation of the triplearch tunnel, therefore triplearch glassstyle central pilot tunnel excavation method is adopted for the tunnel and concrete walls are built for the tunnel to improve the strength between the main tunnels and to provide support bearing point in the temporary tunnel excavation. It is hoped that the design experience described can provide reference for subsequent similar cases.

Key words: triplearch tunnel, closelyspaced tunnel, central pilot tunnel