Experimental Research on the Transverse Effective Bending Rigidity of Shield Tunnels

Zheng, Gang; Lei, Yiwen; Cui, Tingwei; Cheng, Xuesong; Diao, Yu; Zhang, Tianqi; Sun, Jibin

doi:10.1155/2019/2174562

Cited by 17 publications

(4 citation statements)

References 28 publications

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“…Therefore, the effective stiffness ratio of tunnel η (η ≤ 1) is introduced to reflect the weakening effect of segment joints on the tunnel stiffness, i.e., the equivalent stiffness of the tunnel is ηEI, where EI is the bending stiffness of the homogeneous tunnel before stiffness reduction. Some studies [24][25][26][27][28] demonstrated that the value of η is related to the soil conditions, the form of the segment joints, and the manner of segment assembly. In this study, the value of η = 0.75 is adopted, referring to the above studies.…”

Section: Constitutive Model and Parametersmentioning

confidence: 99%

Influenced Zone of Deep Excavation on Adjacent Tunnel Displacement and Control Effect of Ground Improvement in Soft Soil

Liu

Shao

2022

Applied Sciences

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The aim of this study is to predict the influenced zone of deep excavation on adjacent tunnel displacement, evaluate the control effect of ground improvement, and give the optimal parameters for ground improvement. Based on the current research, a series of finite element method (FEM) numerical simulations were conducted to study the deep excavation-induced tunnel displacement behaviors, considering different tunnel positions outside the pit. On this basis, the influenced zone of deep excavation on an adjacent tunnel was divided corresponding to 3-level tunnel displacement control standards. Then, the commonly used control measure of ground improvement was chosen to study the effects of strength, depth, and width of the improved soil outside the pit on the displacement behaviors of the tunnel. An index of tunnel displacement control effectiveness (η) was proposed to quantitively characterize the control effect on tunnel displacement. Considering the control effect and engineering economy, the suggested values of strength, depth, and width of the improved soil were provided. Finally, the control effect of ground improvement outside the pit on the influenced zone of deep excavation was studied using the suggested parameters. The research indicates that the range outside the pit can be divided into: I—primary influenced zone, II—secondary influenced zone, III—general influenced zone, and IV—weak influenced zone. Considering the control effect and engineering economy, it is suggested that the ground improvement strength should be kept within 1.5~2 MPa, the ground improvement depth should be 2 times the excavation depth, and the ground improvement width should be increased as much as possible if the site condition allows. After the ground improvement using the suggested parameters, the scope of the influenced zone of deep excavation is reduced and the I—primary influenced zone no longer exists.

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Section: Constitutive Model and Parametersmentioning

confidence: 99%

Influenced Zone of Deep Excavation on Adjacent Tunnel Displacement and Control Effect of Ground Improvement in Soft Soil

Liu

Shao

2022

Applied Sciences

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“…Empirical methods and theoretical analyses are used to predict surface settlement and stratum movements caused by shield tunnelling [24,25]. Model tests also play an important role in investigating mechanical behaviour of shield tunnelling [26][27][28][29]. Meanwhile, in order to obtain the real data of shield tunnel, construction field monitoring also has been adopted [30,31].…”

Section: Introductionmentioning

confidence: 99%

Study on Construction Influence of Shield Tunnel of Urban Rail Transit on Large‐Section Mining Tunnel

Zhang

Yan

et al. 2020

Advances in Civil Engineering

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Due to the increasingly expanding of urban rail transit, shield tunnelling adjacent to existing tunnels has become more and more common in cities. Construction of new tunnels will pose great risks to the safety of existing tunnels. This paper focused on the influence of shield tunnelling on the large-section mining tunnel in the argillaceous siltstone stratum and proposed the influence zone based on the surface subsidence criterion. By carrying out numerical simulations and model test, the surface subsidence, the internal force of the mining tunnel, and the surrounding rock pressure were monitored and the accuracy of the influence zone was verified. The research shows that the shield machine tunnels forward from one time the excavation diameter before the monitoring section until the monitoring section completes the segment assembly. This process is the main stage that causes the increase in the corresponding surface settlement and the additional displacement of the existing mining tunnel. The excavating tunnel influences on the mining tunnel structure were mainly shown at the vertical additional deformation, which is manifested as the overall floating of the mining tunnel. The influence of internal force was performed as the asymmetric change of internal force of the mining tunnel. The mining tunnel is closer to the shield tunnel, showing more significant changes of the internal force of the structures. The structure near the shield tunnel is strengthened by pressure, and the structure far away from the shield tunnel is more prone to tensile failure.

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“…It is reported that the range of the effective ratio of the transverse bending rigidity value is between 0.09 and 0.23 under straight-jointed condition and 0.30 and 0.80 under stagger-jointed condition. Zheng et al [24] also adopted polyethylene and aluminium wire to fabricate the shield tunnel models, and the effective rigidity ratios of the tunnel were investigated through testing the model under the concentrated load and realistic loading pattern in sandy soil. Taking the Shanghai Yan-Jiang Tunnel as an example, Li et al [25] analysed the influence of buried depth on the effective ratio of the transverse bending rigidity and found that the buried depth has a great influence on η. Feng et al [26] carried out prototype tests on segmental lining structure for shield tunnel with a large cross section and attained the variation pattern of η and ξ with load conditions; the experiment also showed that as the section increases, η increases while ξ decreases.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies mainly focus on the transverse effective bending rigidity ratio in the elastic stage. For example, elastic materials are always used in model tests [22][23][24]. However, the damage process of the material of segment rings as the load increases can also conversely influence the value of the transverse effective bending rigidity ratio.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Transverse Effective Bending Rigidity of Segmental Lining Structures

Tang

Chen

et al. 2020

Advances in Civil Engineering

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The transverse effective rigidity ratio is a key parameter when the uniform rigidity ring model is adopted to design or numerically analyse segmental lining structures commonly used on a shield-driven tunnel. Traditionally, the transverse effective rigidity ratio η is treated as a constant, which can be evaluated through theoretical analysis and model tests. In this study, scale models were designed and tested to investigate the variation of the transverse effective rigidity ratio in the segmental linings’ flattening deformation process. The test results suggested that in the elastic stage, the transverse effective rigidity ratio fluctuated between 0.667 and 0.734 for the stagger-jointed rings and fluctuated between 0.503 and 0.642 for the straight-jointed rings. When segmental linings were squashed and started to crack at the circumferential joints, the transverse effective rigidity ratio decreases sharply. Then, a regression equation was obtained to fit the variation trend of η with the increase of horizontal convergence to the outer-diameter ratio (ΔD/Dout). Finally, in a case study, the regression equation was adapted to determine the value of η of an operated shield tunnel which was once surcharged accidentally and deformed severely so as to numerically predict the prospective deformation induced by the upcoming adjacent excavation. Numerical results indicated that as the value of η decreases, the horizontal convergences of shield tunnel induced by adjacent excavation increase significantly and even more than doubled in the case study. Comparatively, through taking account of the operating tunnels’ exiting transverse deformation, the predicted deformation tends to be unfavourable.

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Experimental Research on the Transverse Effective Bending Rigidity of Shield Tunnels

Cited by 17 publications

References 28 publications

Influenced Zone of Deep Excavation on Adjacent Tunnel Displacement and Control Effect of Ground Improvement in Soft Soil

Influenced Zone of Deep Excavation on Adjacent Tunnel Displacement and Control Effect of Ground Improvement in Soft Soil

Study on Construction Influence of Shield Tunnel of Urban Rail Transit on Large‐Section Mining Tunnel

Experimental Study on the Transverse Effective Bending Rigidity of Segmental Lining Structures

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