Study on Construction Influence of Shield Tunnel of Urban Rail Transit on Large-Section Mining Tunnel

Abstract

Due to the increasingly expanding of urban rail transit, shield tunnelling adjacent to existing tunnels has become more and more common in cities. Construction of new tunnels will pose great risks to the safety of existing tunnels. This paper focused on the influence of shield tunnelling on the large-section mining tunnel in the argillaceous siltstone stratum and proposed the influence zone based on the surface subsidence criterion. By carrying out numerical simulations and model test, the surface subsidence, the internal force of the mining tunnel, and the surrounding rock pressure were monitored and the accuracy of the influence zone was verified. The research shows that the shield machine tunnels forward from one time the excavation diameter before the monitoring section until the monitoring section completes the segment assembly. This process is the main stage that causes the increase in the corresponding surface settlement and the additional displacement of the existing mining tunnel. The excavating tunnel influences on the mining tunnel structure were mainly shown at the vertical additional deformation, which is manifested as the overall floating of the mining tunnel. The influence of internal force was performed as the asymmetric change of internal force of the mining tunnel. The mining tunnel is closer to the shield tunnel, showing more significant changes of the internal force of the structures. The structure near the shield tunnel is strengthened by pressure, and the structure far away from the shield tunnel is more prone to tensile failure.