scholarly journals A numerical study on the effect of train-induced vibration in shield tunnel

2014 ◽  
Vol 16 (2) ◽  
pp. 261
Author(s):  
Kwak
Keyword(s):  
Numerical Study ◽  
Shield Tunnel ◽  
Train Induced Vibration

scholarly journals Failure Characteristics of Joint Bolts in Shield Tunnels Subjected to Impact Loads from a Derailed Train

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Qixiang Yan ◽  
Zhixin Deng ◽  
Yanyang Zhang ◽  
Wenbo Yang
Keyword(s):  
Impact Load ◽  
Numerical Study ◽  
Design Method ◽  
Shield Tunnel ◽  
Failure Behavior ◽  
Impact Loads ◽  
Fe Model ◽  
Fe Modelling ◽  
Bolt Failure ◽  
The Impact

Impact loads generated by derailed trains can be extremely high, especially in the case of heavy trains running at high speeds, which usually cause significant safety issues to the rail infrastructures. In shield tunnels, such impact loads may not only cause the damage and deformation of concrete segments, but also lead to the failure of segmental joint bolts. This paper presents a numerical study on the failure behavior of segmental joint bolts in the shield tunnel under impact loading resulting from train derailments. A three-dimensional (3D) numerical model of a shield tunnel based on the finite element (FE) modelling strategy was established, in which the structural behavior of the segmental joint surfaces and the mechanical behavior of the segmental joint bolts were determined. The numerical results show that the occurrence of bolt failure starts at the joints near the impacted segment and develops along the travel direction of train. An extensive parametric study was subsequently performed and the influences of the bolt failure on the dynamic response of the segment were investigated. In particular, the proposed FE model and the analytical results will be used for optimizing the design method of the shield tunnel in preventing the failure of the joint bolts due to the impact load from a derailed HST.

A Numerical Study of the Impact of Tunnel Depth on Surface Displacement in Shield Tunnel Construction

2013 ◽  
Vol 423-426 ◽  
pp. 1248-1252
Author(s):  
Hui Ting Zhan ◽  
Hong Yuan ◽  
Jia Yu Wu ◽  
Yu Sen Yuan
Keyword(s):  
Numerical Study ◽  
Surface Displacement ◽  
Soil Surface ◽  
Rate Of Change ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Displacement Curve ◽  
3D Finite Element Method ◽  
Tunnel Depth ◽  
The Impact

Using 3d finite element method can simulate the process of shield tunnel construction. The paper studies the impact of different tunnel depth on the deformation of soil, when considering different excavation steps in the process of tunnel construction. The results show that the shallower the tunnel depth, and the greater the amount of the surface displacement during the tunnel construction. In the process of the tunnel excavation, the soil surface displacement in front of the shield machine is the result of superposition of the uplift and subsidence. When the tunnel depth increases, the surface displacement curve becomes smoother, and the rate of change becomes slower.

scholarly journals Numerical Study on the Disturbance Effect of Short-Distance Parallel Shield Tunnelling Undercrossing Existing Tunnels

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zhen Huang ◽  
Chenlong Zhang ◽  
Helin Fu ◽  
Huangshi Deng ◽  
Shaokun Ma ◽  
...  
Keyword(s):  
Numerical Model ◽  
Short Distance ◽  
Maximum Stress ◽  
Numerical Study ◽  
Soil Layer ◽  
Field Monitoring ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Double Line ◽  
Shield Tunnelling

The construction of new tunnels poses a threat to the operational safety of closely existing tunnels, and the construction mode of parallel undercrossing over short distances has the most significant impact. In this study, a new double-line shield tunnel parallel undercrossing of existing tunnels in Hefei, China, is taken as an example. A three-dimensional (3D) numerical model using FLAC3D finite difference software was established. The dynamic construction of the new double-line shield tunnel undercrossing the existing subway tunnel over a short distance and in parallel was simulated. The pattern of existing tunnel settlement and change in lining stress caused by the shield tunnelling process were analyzed. The reliability of simulation was verified through field-monitoring data. Finally, based on the numerical model, the effects of change in stratum sensitivity on the settlement of existing tunnel, lining internal force, and surface settlement are discussed. The results show that during shield tunnelling, the maximum ground settlement is 3.9 mm, the maximum settlement at the arch waist of existing tunnel near the new tunnel is 7.75 mm, and the maximum vault settlement is 5.38 mm. The maximum stress of lining of existing tunnel before the excavation is 7.798 × 105 Pa. After the construction of double-line shield tunnel, the maximum stress of lining is 1.124 × 106 Pa, an increase of 44% than that before the construction. The surface settlement and tunnel settlement are sensitive to the weakening of soil layer strength, and lining stress is not affected by the weakening of soil layer strength. The field-monitoring results are consistent with the numerical simulation results, and the model calculation is reliable. This study plays an important role in ensuring construction safety and optimizing the construction risk control of a tunnel.

scholarly journals Numerical Study on the Fracture Properties of Concrete Shield Tunnel Lining Segments

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Longgang Tian ◽  
Xiao Wang ◽  
Ziling Cheng
Keyword(s):  
Crack Propagation ◽  
Bearing Capacity ◽  
Numerical Study ◽  
Numerical Models ◽  
Three Dimensional ◽  
Complex Loading ◽  
Tunnel Lining ◽  
Shield Tunnel ◽  
Loading Eccentricity ◽  
Element Method

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.

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