Abstract:

The influence of rockspan ratio and coverspan ratio on the cover depth of a shallowcovered mined station of Qingdao Metro is studied by using numerical simulation method and in terms of several indices. The study results show that: 1) In intensely weathered to slightly weathered granite strata, compared to the soil cover, the rock cover plays more important role on the stability of the surrounding rock and is more helpful for the stability of the tunnel; 2) In the typical soilrock strata in Qingdao, the stability of the tunnel is most sensitive to the depth of the rock cover, with the coverspan ratio at the second place. And the dead weight of the cover may impact the deformation and force conditions of the tunnel after construction. 

Key words: soilrock strata, cover depth, coverspan ratio, rockspan ratio, deformation, internal force