Study on Structural Design and Construction Procedure for a Triple Arch Railway Tunnel

In consideration with geological and hydrogeological conditions of a four track railway tunnel in the new railway line from Lanzhou to Chengdu in China, A scenario of triple arch railway tunnel is presented in the paper. Curved side wall, vault and invert are adopted in its composite lining. Two intermediate concrete walls are set in the tunnel lining structure. In order to support rock pressure induced by rock mass above crown, two pilot drifts and bench cut method are utilized to build the triple arch tunnel. As for its portal section, pipe roof protection and advance grouting pipes are efficient measures to resist rock pressure and keep the stability of rock mass during its excavation. The method to excogitate the triple arch railway tunnel in this paper may guide the design and construction of such kind of triple arch tunnel under similar conditions.