Abstract:

The exit of Dongtianshan super long highway tunnel in Xinjiang G575 line is over shallow buried through a large landslide body. In order to ensure the safe and fast tunneling in the landslide body and control the risks of tunnel deformation, collapse, slip and so on, the "coverexcavation+selfdrilling pipe shed" portalin method is adopted. Under the protection of the initial supporting steel frame "arch" formed by the coverexcavation method, the safety of the selfdrilling pipe shed construction in the "under arch" hole is ensured. In addition, the advanced grouting for selfdrilling pipe shed is used to reinforce the surrounding rock of the loose slope and realize the safe and fast tunneling. Through the comparison of different tunneling schemes and field practices, with the monitoring of the surface subsidence of the vault, the crown settlement and the horizontal convergence in the tunnel during the construction, the regression analysis shows that: the "coverexcavation+selfdrilling pipe shed" construction method can not only ensure the safety portalin, but also save the construction time, and has no effect on the overall stability of the landslide body. 

Key words: super long highway tunnel, landslide body, coverexcavation method, selfdrilling pipe shed, portalin