Analysis on the Influence of Dismantling Temporary Lining of Closely-Undercrossing Subway

摘要

Due to the limited space in urban area, subway tunnels have to be designed and constructed with marginal clearance between each other. In the construction of subway tunnels, the installation and dismantling of temporary lining prone to affect the existing subway and new subway. In this paper, based on the Nijiaqiao Station Project in Chengdu Metro, stress state and deformation of the existing subway and the new subway, induced by dismantling of temporary lining, are compared and analyzed. It is found that different installation sequence of lining and dismantling temporary lining will affect the deformation of the subway, especially in the floor. The deformation and stress conditions of the structure are the least affected when all secondary linings are constructed in the first place and then all temporary linings are dismantled; and condition II is the worst and leads to excessive deformation and stress. Based on the analysis of the construction efficiency and influence of dismantling temporary lining, it is suggested that the combination form of divisional lining and dismantling temporary lining (i.e., condition III) can be adopted for the construction of closely-undercrossing subway. Finally, it is found that the field monitoring results are basically consistent with the simulation results, which verifies the validity of the numerical simulation. The results obtained in this paper can provide some vital references for the design and construction of similar projects (i.e., closely-undercrossing cases) in the future.