General solutions for the longitudinal deformation of shield tunnels with multiple discontinuities in strata

Cheng, Hongzhan; Chen, Renpeng; Wu, Huai-Na; Meng, Fanyan; Yi, Yaolin

doi:10.1016/j.tust.2020.103652

Cited by 50 publications

(23 citation statements)

References 45 publications

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“…In the analysis of the longitudinal deformation of a tunnel segmental lining, the circular joint behaviour is critical (Cheng et al 2021(Cheng et al , 2020Li et al 2019;Liao et al 2008;Liu et al 2021a;Wu et al 2015Wu et al , 2018. Based on the beam theory, Shiba et al (1988) simplified the segmental lining as a continuous beam with a reduced stiffness due to the presence of joints, but the influence of the segments and the joints separately on the damage of the segmental lining cannot be discussed using these simplified methods.…”

Section: Introductionmentioning

confidence: 99%

The Buoyancy of the Tunnel Segmental Lining in the Surrounding Filling Material and its Effects on the Concrete Stress State

Han

Oreste

2022

Geotech Geol Eng

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Segmental lining is subject to significant upward buoyancy forces when a grouting material (slurry), initially fluid, is adopted to fill the gap between its external profile and the wall of a tunnel excavated with a TBM machine. The analysis of the effects of these forces is important in order to correctly dimension the segmental lining and avoid damage to the lining and subsequent costly maintenance and restoration actions. Given the complexity of the behavior of a segmental lining consisting of segmental rings and circular joints that alternate in the longitudinal direction of the tunnel, a specific numerical model has been implemented, adopting the Finite Element Method (FEM). This model is able to obtain the development of the vertical displacements of the segmental lining starting from the TBM tail, together with the bending moments and the shear forces induced inside it. The developed model is able to assess the risks of breaking and damaging the concrete and steel bolts that are used to connect the segmental rings at the circular joints; therefore, it represents a useful design tool for being able to correctly dimension the segmental lining also in relation to the risks produced by the appearance of considerable buoyancy forces around it, due to the presence of the initially fluid filling material. The proposed numerical model was applied to a real case (Ningbo metro tunnel) and allowed to obtain satisfactory results from the comparison of the calculated displacements with in situ measurements. Some sensitivity analyzes developed on the studied case have made it possible to detect which are the influencing parameters that have the greatest impact on the behavior of segmental lining in the presence of the studied buoyancy forces.

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Section: Introductionmentioning

confidence: 99%

The Buoyancy of the Tunnel Segmental Lining in the Surrounding Filling Material and its Effects on the Concrete Stress State

Han

Oreste

2022

Geotech Geol Eng

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“…A serious safety accident will be caused by slight carelessness [6]. At present, some scholars have carried out relevant studies on segment lining structures [7][8][9][10][11][12][13][14][15][16][17][18][19][20] and shield reinforcement technology [21][22][23][24][25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

“…A risk assessment methodology that aims to evaluate the risks of the circumferential cracks of preexisting shield tunnels was proposed to ensure the security of existing tunnels under deep excavation during construction [17]. Considering the stratum with multiple discontinuities, a method was proposed to evaluate the longitudinal deformation caused by potential disturbance after shield tunnel construction, which can better predict the deformation characteristics of a shield tunnel, such as settlement, dislocation and the opening of joints [18]. When a shield tunnel is subjected to earthquakes and longitudinal deformation of the stratum, the segment ring may open along the longitudinal direction, and the tensile characteristics and failure modes of circumferential joints and bolted joints can be analyzed [19,20].…”

Section: Introductionmentioning

confidence: 99%

Study on Longitudinal Stress Relaxation Effect and Reinforcement Technology of Segment Lining during Shield Docking

Geng

Yuan

Wang³

et al. 2022

Applied Sciences

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Shield docking technology is widely used in underwater shield tunnels. As the technology is not perfect, the instability of the tunnel face and the stress relaxation of segment lining caused by shield dismantling need to be solved. Using a cross-sea tunnel project, the segment lining reinforcement technology with steel channel in the process of shield docking is studied. The longitudinal stress relaxation effect of segment lining after thrust unloading is analyzed, and the theoretical solution of segment circumferential joint opening, with or without steel channel reinforcement, is derived. The accuracy of the theoretical model and the shell connector numerical model is verified by comparison. Then, the influence of key parameters, such as reinforcement range, steel channel quantity and steel channel model, on reinforcement effect is discussed. The results show that: (1) with the increase in the range of reinforcement, the maximum longitudinal displacement and the opening of the circumferential joints decrease first and then increase; (2) with the increase in the quantity and model of the steel channel, the maximum longitudinal displacement and the opening of the circumferential joints gradually decrease, and the reduction rate also decreases. The farther away from the shield tail, the weaker the reinforcement effect on segment lining.

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“…Shield tunneling is extensively adopted as a common excavation method, which brings about the adverse consequence that the surrounding soil is inevitably disturbed, causing cracks, leakage, and other adverse impacts on adjacent existing structures [1,2]. Many scholars have conducted investigations on these adverse effects on existing tunnels [3][4][5]. In general, the methodologies can be classified into four categories of approaches: theoretical analysis [6][7][8], numerical simulation [9][10][11][12], physical model testing [13,14], and field monitoring [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Settlement of an Existing Tunnel Induced by Crossing Shield Tunneling Involving Residual Jacking Force

et al. 2022

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An analytical formulation involving residual force is proposed to predict the displacement of an existing structure by simplifying the tunnel as an infinite Euler–Bernoulli beam resting on a two-parameter Pasternak foundation. The feasibility is confirmed by two actual measurements at sites in the published literature. Parametric studies—including consideration of jacking force alone, jacking force and ground loss, and jacking force and equivalent bending stiffness—are carried out to study the influence on the deformation of the existing tunnel. The results show that the residual jacking force can decrease the settlement of the existing tunnel, but the significance of its effect varies under different engineering conditions. With the increase in ground loss, the beneficial effect of jacking force in preventing further aggravation of tunnel settlement gradually becomes obvious, and the jacking force can reduce the deformation more effectively when the tunnel has lower bending stiffness. As a result, it is recommended that some effective measures should be adopted to maintain sufficient residual jacking force in the segments, so as to prolong the life of the tunnel.

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General solutions for the longitudinal deformation of shield tunnels with multiple discontinuities in strata

Cited by 50 publications

References 45 publications

The Buoyancy of the Tunnel Segmental Lining in the Surrounding Filling Material and its Effects on the Concrete Stress State

The Buoyancy of the Tunnel Segmental Lining in the Surrounding Filling Material and its Effects on the Concrete Stress State

Study on Longitudinal Stress Relaxation Effect and Reinforcement Technology of Segment Lining during Shield Docking

Settlement of an Existing Tunnel Induced by Crossing Shield Tunneling Involving Residual Jacking Force

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