Abstract
It is very important to evaluate the structural behavior of shield tunnel lining reasonably to ensure the safe operation and maintenance of subway trains. In this paper, by virtue of the resilience theory, the resilience evaluation of the existing shield tunnel lining induced by the symmetrical excavation of adjacent foundation pit is conducted using the numerical simulation. Firstly, the structural behavior index of the shield tunnel lining is defined. Moreover, using the evolution of structural behavior index along with the symmetrical excavation steps of adjacent foundation pit, the calculation method of the resilience index of the shield tunnel lining and grade of resilience are proposed. Secondly, numerical simulation is conducted to compare the degree of influence of three different block symmetrical excavation methods of the adjacent foundation pit on the structural deformation of existing shield tunnel lining. Finally, based on the proposed resilience evaluation method, the structural deformation index and the resilience index of the existing shield tunnel lining are calculated under three different block symmetrical excavation methods, which indicates that the control effect of different block symmetrical excavation methods of the adjacent foundation pit varies greatly. Moreover, it is necessary to adopt the fine excavation method of foundation pit by sections to better control the deformation of the existing shield tunnel lining.
Highlights
To ensure the safe operation and maintenance of subway trains, there are strict deformation control requirements for metro shield tunnels
The results show that the longitudinal deformations of the existing shield tunnel linings vary greatly under different symmetrical excavation methods
In this paper, based on resilience theory, the analysis of the resilience evolution of the existing shield tunnels induced by the symmetrical excavation of an adjacent foundation pit is conducted by virtue of numerical simulations
Summary
To ensure the safe operation and maintenance of subway trains, there are strict deformation control requirements for metro shield tunnels. There is very little literature on the subject of the resilience evolution analysis of the existing shield tunnels induced by the influence of adjacent foundation pit excavations based on numerical simulations. An analysis of the resilience evolution of the existing shield tunnels induced by the symmetrical excavation of an adjacent foundation pit is conducted by virtue of numerical simulation. The Plaxis 3D finite element software is used to carry out the comparative analysis of the degree of influence of three different block symmetrical excavation methods of an adjacent foundation pit on the structural deformation of the shield tunnel lining. Based on the proposed resilience evaluation method, the structural deformation index and the resilience index of the existing shield tunnel lining under three different block symmetrical excavation methods are calculated and studied. Ωmax where Q denotes the structural behavior index; ωmax presents the specified warning value in the Chinese Standard CJJ/T202-2013; and ω is the structural deformation of tunnel lining
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