Abstract:

Weihe tunnel on BaojiLanzhou passengerdedicated railway is 10.016 km long. Three vertical shafts and two inclined shafts are installed for the tunnel so as to speed up the tunnel construction. With 54.4 m depth and 230 m2 excavation crosssection area, No. 1 vertical shaft of Weihe tunnel is an extralarge and deep shaft. The vertical shaft is located in hardsoft heterogeneous ground. Therefore, it is of great significance to select a safe and rational structure type, as well as a proper construction method, for the vertical shaft. Support structure consisting of secant piles and shotcreting and rockbolting, topdown construction method, as well as inner lining, are selected for the vertical shaft on basis of the actual geological conditions and the stress analysis results. Bracing made of reinforced concrete is installed when the vertical shaft is backfilled, so as to ensure the structural safety of the tunnel. This paper can provide reference for the design of similar projects in the future.

Key words: Weihe tunnel, extralarge and deep vertical shaft, retaining structure, secant pile, shotcreting and rockbolting