Numerical Investigation on the excavation methods for Large Span Dome in Deep Buried Railway Station

Abstract

Badaling Great Wall Station, excavated with drilling and blasting method, is the first underground railway station in China. The domeshaped distribution hall is of the maximum span within the entire station and is rare in underground transit projects. To find out an optimal excavation method, the sector method and the ring method are proposed and compared by threedimensional numerical simulation in this paper. The results are as follows: (1) Dome excavated by the modified ring method is of better shape with small and uniform convergence, when compared to the sector method. (2) For the modified ring method, the primary support can be closed in time under the protection of the reserved core rock. Hence, the structure performs well in restraining the surrounding rock from loosening, with larger bending moment and more uniform corresponding axial force response than that induced by the sector method. (3) The modified ring method is recommended for the large span dome. And the reserved core rock plays a beneficial role to support the surrounding rock, which helps to guarantee safety during construction. This research can make guidance for similar projects.