Experimental investigation of the ultimate bearing capacity of continuously jointed segmental tunnel linings

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Summary A nonlinear hybrid method is developed for multiscale analysis of a bearing‐capacity test of a real‐scale segmental tunnel ring subjected to point loads. The structural analysis consists of two parts. Part I refers to modeling of bending‐induced tensile cracking of the segments, resulting from the external loading. The segments are subdivided into elements, according to the crack spacing. Each element is either intact or contains one central crack band, flanked by lateral undamaged domains. A multiscale model for tensile softening of concrete is used to describe the progressive deterioration of the crack bands. After iterative determination of their state of damage, the effective bending and extensional stiffnesses of the corresponding elements are quantified by means of Voigt‐Reuss‐Hill estimates. The effective stiffnesses are used for linear‐elastic simulations of the segmental tunnel ring. Part II refers to the relative rotation angles at the joints, which are estimated from monitoring data, using the Bernoulli‐Euler hypothesis. Since the validity of this hypothesis is questionable for neck‐like joints, the relative rotation angles are post‐processed such that they refer to rigid body displacements of the segments. The following conclusions are drawn: The presented approach yields good estimates of crack widths. Relative rotation angles at the joints mainly result in rigid body displacements of the segments, governing the convergences. Because realistic interface models are lacking, hybrid analysis based on displacement‐monitoring data allows for performing ultimate‐load analysis of segmental tunnel rings.

Section: Experimental Datamentioning

confidence: 95%

Section: Experimental Datamentioning

confidence: 99%

Section: Experimental Datamentioning

confidence: 99%

Section: Experimental Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On a nonlinear hybrid method for multiscale analysis of a bearing‐capacity test of a real‐scale segmental tunnel ring

Zhang

Mang

Liu

et al. 2019

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A computational framework to predict the water‐leakage pressure of segmental joints in underwater shield tunnels using an advanced finite element method

Gong

Ding

2018

Summary The construction of shield tunnels under riverbeds and seabeds has considerably increased over the past decades. Due to the ultra‐high water head, water leakage through tunnel joints is a major concern during a tunnel's service life. One practical solution to prevent groundwater penetration is to implement ethylene‐propylene‐diene‐monomer gaskets at the segmental joints. However, numerical simulation of fluid pressure penetration into rubber materials remains a challenging problem in computational mechanics. Severe mesh distortions can occur due to large deformation. Consequently, a convergent solution is difficult to achieve. This paper presents an Abaqus‐based numerical framework to solve the previously mentioned problem using the implicit finite element solver. The key aspects of this framework are twofold: (1) a remesh and re‐map algorithm to overcome the excessive mesh distortion, and (2) simulation of fluid penetration into the contact interface of the gaskets to reproduce the water‐leakage process at the tunnel joints. The proposed framework is first tested to simulate the gasket‐in‐groove mechanical behavior and is then validated using experimental data and the solution produced by an explicit finite element solver. The developed framework is then adopted to predict the water‐leakage pressure at gasketed tunnel joints to illustrate the practical applications. Finally, the numerical results are compared with experimental data to demonstrate the accuracy and robustness of the proposed method and confirm its superiority and effectiveness over existing methods. This novel method can be used by tunnel designers to analyze and estimate the waterproof behavior of gasketed joints in shield tunnels without performing extensive experimental testing works.

A comparative investigation between the beam spring method and the modified routine method in special‐section shield tunnels: A case study for quasi‐rectangular tunnels

Zhang

Corte

Liu

et al. 2022

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The modified routine modelling (MRM) and the beam spring modelling (BSM) are two of the classical design methods for circular shield tunnels, but a comparison between their applications in special-section shield tunnels (SSSTs) has not yet been conducted. In this study, these two methods are investigated and compared specifically for the case of quasi-rectangular shield tunnels (QRSTs). While the MRM gives acceptable results for axial force values, some critical bending moments in joint sections and segment sections can be overestimated or underestimated, not giving accurate values for design. It is demonstrated that the MRM cannot precisely predict the degree of bending moment transfer and convergence deformations of the studied SSST, and should only be used in preliminary design. On the other hand, deeper insights into the mechanical behaviour of the QRST lining structure can be gained through the analysis of the BSM. The staggered assembly pattern results in a bending moment transfer between rings and the relatively stiff area sustains the transferred moment from its neighbouring less stiff areas. For most of the longitudinal joints, 20% to 40% of bending moment is redistributed to its neighbouring segments. The transfer increases the nonsymmetric distribution of bending moments in the two halves of a QRST lining ring. This characteristic does not exist in a traditional circular shield tunnel but needs due attention to the types of shield tunnels with two compartments in one tube. Finally, the influences of different parameters related to the assumed pressures and soil reactions are discussed.