3D impact zoning of super-close and over-crossing existing tunnels of New Airport Line of Beijing Metro and its application

In order to scientifically and reasonably formulate the super-close construction and reinforcement scheme of urban underground engineering, the three-dimensional impact zoning and its application are investigated by using the numerical simulation and field monitoring based on the New Airport Line of Beijing Metro super-close to and overcrossing the existing Line 10. The expressions for horizontal and vertical impact zoning relying on the project are deduced, the 3D impact zoning based on the uplift value of the existing tunnel is determined, and the countermeasures for each impact zoning are put forward. Considering the construction space and economic indice, the reinforcement measures based on 3D impact zoning of the supporting project are optimized. Through the comparative analysis of numerical simulations, it can be seen that the optimized reinforcement measures of retaining wall meet the construction safety requirements. The recommended optimal reinforcement measures of retaining wall are adopted for the construction of the supporting project. The on-site monitoring data show that the construction influence laws of the displacement change of the arch crown of the existing tunnel are consistent with the numerical simulation analysis, and the displacement values are less than the control standard, indicating that the proposed 3D impact zoning and reinforcement measures can ensure the construction safety of the supporting project. The research results may provide reference for the construction safety control of similar projects.