Abstract
Shield tunnel lining structure is usually under very complex loading conditions in the underground space. As a kind of the common concrete structures, any defect in the tunnel lining segment may deteriorate its bearing capacity and even cause severe disasters. Three-dimensional numerical models of shield tunnel lining segments with initial cracks are built using the Symmetric Galerkin Boundary Element Method- (SGBEM-) Finite Element Method (FEM) Alternating Method. The cracking load and ultimate load of the tunnel segments are obtained, and crack propagation under fatigue load is also simulated by employing the Paris Fatigue Law. Results show that loading eccentricity has a very large influence on the bearing capacity of the cracked lining segment; the larger the loading eccentricity, the smaller the bearing capacity. Deformation and damage of the lining segment show obvious phases, which consist of the initial crack, cracking stage, steady crack propagation, unsteady crack propagation, and eventual failure.
Highlights
As the construction technology in underground engineering develops rapidly nowadays, the shield tunnel has gradually become the main form of urban metro tunnel
A novel loading setup was developed by Huang et al [11] for performing full-scale loading tests on “standing” segmental lining of a subrectangular shield tunnel, which for the first time allowed the mechanical behavior of the segmental lining subject to self-weight to be assessed in a full-scale loading test
Almost all of these researches are mainly focused on intact tunnel lining structures, while little research has been done on the mechanical behavior and fracture properties of the shield tunnel lining segment with initial flaws, and researches on the propagation law of existing cracks and the failure mode of a cracked tunnel lining structure are rare
Summary
As the construction technology in underground engineering develops rapidly nowadays, the shield tunnel has gradually become the main form of urban metro tunnel. Based on the field investigation and analysis, Wang et al compared and analyzed the mechanical characteristics of the segment structure in shield tunnels under the circumstances of different concrete spalling regions by the method of the similarity model experiment [10]. Many other researches [14,15,16,17,18,19] were conducted by numerical simulation or in situ test to study the fracture evolution and failure process of underground engineering Almost all of these researches are mainly focused on intact tunnel lining structures, while little research has been done on the mechanical behavior and fracture properties of the shield tunnel lining segment with initial flaws, and researches on the propagation law of existing cracks and the failure mode of a cracked tunnel lining structure are rare. Ω x ep Figure 1: A solution domain with source point x and target point ξ
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