Abstract:

Changshao Expressway tunnels with small spacing have complicated and special topographies; especially at the region of outlet, the provincial expressway S102 is only 5 meters over the vault of the left tunnel; and the right tunnel is pressed by an unsymmetrically pressure. In order to study the effects of excavation types on surface settlement and stability of surrounding rockmass, a three-dimensional model which is corresponding to realistic landform is built to simulate distribution of plastic zones, deformation of surrounding rockmass and surface settlement by three different excavation types which are bench cut method, core rock cut method and single-side drift method. Two practical excavation methods are recommended after simulating. Comparison of surface settlement is made between simulating result and field observations. The results show that bench cut method can be used to traverse provincial expressway. The surface settlement during excavation is small and surrounding rockmass is stable.

Key words: tunnel engineering, traversing provincial expressway, excavation methods simulation, shallow tunnels, unsymmetrical pressure