ABSTRACT
The multi-arch tunnel has been a vital component of mountainous expressway construction. In this work, a multi-arch tunnel with central drift excavation method in soft ground under shallow topography as well as shallow-unsymmetrical topography is simulated in conjunction with field application. Mechanical responses such as vault settlements and horizontal convergence deformations at the shoulder are analyzed for parallel sub-tunnels. Lastly, the crucial construction step as well as with the construction interference is revealed. The vault settlement is primarily triggered by the excavation of the upper bench area itself. The horizontal convergence deformation at the shoulder mainly increases during the excavation of the upper bench area itself as well as the middle bench area. Excavation of the central drift causes the initial disturbance. The subsequent sub-tunnel indeed adversely affects the stability of the antecedent one. The unsymmetrical topography aggravates negative mechanical responses and construction interference.
