Seismic response of immersed tunnel in liquefiable seabed considering ocean environmental loads

Zhao, Kai; Zhu, Shengdong; Bai, Xiaoxiao; Wang, Qiuzhe; Chen, Su; Hu, Zhuang; Chen, Guoxing

doi:10.1016/j.tust.2021.104066

Cited by 14 publications

(6 citation statements)

References 44 publications

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“…Tunneling‐induced vertical and lateral movements of liquefiable sand are higher compared with the pure solid state of the soil. In addition, liquefaction phenomena of different ground conditions, including (a) soil with pile, (b) soil with a tunnel, (c) soil with a tunnel and pile, and (d) saturated soil with a tunnel of the sea bed, have been described by several authors based on various research methods such as numerical and analytical analyses, the centrifuge test, and the shaking table test (Finn & Fujita, 2002; Liyanapathirana & Poulos, 2002; Liyanathirana & Poulos, 2002; Orang et al, 2021; Taylor & Madabhushi, 2020; Wang et al, 2022; Yue et al, 2020; Zhao et al, 2021). Normally, liquefaction occurs due to seismic shaking, which impacts surface and underground structures.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear anisotropic finite element analysis of liquefiable tunnel–sand–pile interaction under seismic excitation

Haque

2023

Deep Underground Science and Engineering

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Nonlinear time‐history analysis can be used to determine the liquefiable behaviors of the tunnel–sand–pile interaction (TSPI) model with the consideration of sand anisotropy. This study presents the nonlinear response of the TSPI model with the existence of liquefaction under seismic excitation. The analysis reveals that tunnel and pile behave as isotropic elements, while sand shows isotropic, orthotropic, and anisotropic characteristics. Three constitutive models including UBC3D‐PLM (two yield surfaces associated with the hardening rule), NGI‐ADP (yielding with associated plastic potential function), and a user‐specified constitutive model are adopted to evaluate the isotropic, orthotropic, and anisotropic behaviors of sand. On this basis, two finite element‐based codes (ETABS 18.1.1 and Plaxis 3D) are used to evaluate sand behaviors and responses. Responses of the tunnel, sand, pile, and excess pore pressure ratio are recorded in the interaction zone by varying the pile diameter, tunnel diameter, and tunnel–pile clearance. Compared with the orthotropic and isotropic conditions, lower variations of results are found in the anisotropic condition, except for the case of generation of excess pore pressure. In addition, the present reanalysis results are in agreement with previous analytical and case study results, which further indicates the effectiveness of the finite element‐based numerical codes.

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Section: Introductionmentioning

confidence: 99%

Nonlinear anisotropic finite element analysis of liquefiable tunnel–sand–pile interaction under seismic excitation

Haque

2023

Deep Underground Science and Engineering

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“…When seismic waves are transmitted to the seabed and seawater, the effect of the presence of seawater on the propagation of seismic waves and energy absorption leads to a change in the vertical frequency of the structure, which attenuates the amplitude of seismic waves during propagation [8,9]. The ability of the seabed to enhance the seismic defenses of tunnels has been demonstrated when seismic SV waves are incident at different angles on the multilayered seabed [10], and the single-layered seabed [11],.…”

Section: Introductionmentioning

confidence: 99%

Deformation and Stress Analysis of Pile-Supported Immersed Tunnels under Seismic Loads

Zhuang,

Fan,

et al. 2023

Applied Sciences

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The stress and deformation of pile-supported immersed tunnels under seismic loads is a critical issue in tunnel design. This paper utilizes ABAQUS (version 2020) finite element software to analyze the seismic load response of the sand compaction pile-immersed tunnel–seawater pressure (SIS) system, which is verified by a physical model. The study shows that the suppression effect of the seawater on the vertical frequency of the tunnel increases with depth. When the replacement rate of the piled foundation reaches 50%, the deformation of the tunnel “H-shaped” structures increases, which also changes the vertical frequency of the tunnel. However, the presence of the suppression effect causes resonance injury at the far end of the tunnel from the earthquake source, resulting in a shift of the peak stress point. It was also found that seawater pressure affects the resistance–deflection (p-y) at the tip of the pile more than at the end of the pile. The slenderness ratio (γ) of the pile affects the p-y value at the end of the pile more than at the tip of the pile. The connection between the piled foundation and the tunnel is most stable when γ is in the range of 9.25 to 15.

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“…e fundamental problems existing in their applications have also received more and more attention. Although researchers have conducted relevant studies on pipe segment prefabrication [1], oating and sinking [2], bearing characteristics [3], operation and maintenance [4], and seismic response [5] of immersed tube structures, there are still some shortcomings. e bearing characteristics of immersed tube structures include a segmented body and a joint.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Characteristics of Variable Cross‐Section Immersed Tunnels under Spatial Differential Settlement

Yang

Wang

Wei

et al. 2022

Advances in Civil Engineering

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This work establishes a fine model reflecting the characteristics of immersed tube structures to study the spatial mechanical characteristics of variable cross section immersed tunnels. Then, the mechanical behavior of the pipe segments under differential deformation is explored, based on which we propose a formula for estimating the shear key force and analyze the corresponding failure mechanism and failure mode. Thus, the critical points of the pipe segment design are specified. The results show that, first, the variable cross section segment bears more sectional internal force (over 47%) than the uniform cross section segment in actual cases, which should be fully considered in practical reinforcement design. Bearing deformation alternatively occurs at different shear keys, implying an apparent spatial stiffness matching problem. Second, the pipe segments show overall settlement under longitudinal bending, failing to satisfy the assumption of deformed plane sections. The force on the shear keys varies with the quadratic function of the longitudinal bending degree, and the dislocation magnitude has a positive near-linear relationship with the bending degree. Third, when subjected to torsion, the shear keys of the weak sidewalls are sheared to resist torsion. Then, this force is laterally transferred to the top and bottom plates and jointly shared by the adjacent shear keys, explaining why shear is adjusted with structural deformation. Fourth, under the action of spatial differential deformation, the shear force is mainly undertaken by the vertical shear keys. When the structure is subjected to bending, compression and shear failure occur at the end angle of the middle wall shear key, and its root junction experiences tension and shear failure. When subjected to longitudinal torsion, the local tension and shear failure at the root of the shear key on the soft subgrade side cause a joint failure. Finally, based on the bearing characteristics, failure mechanism, and failure mode of variable cross section immersed tunnels, the idea of strengthening immersed tube structures is put forward, which can guide similar engineers.

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Seismic response of immersed tunnel in liquefiable seabed considering ocean environmental loads

Cited by 14 publications

References 44 publications

Nonlinear anisotropic finite element analysis of liquefiable tunnel–sand–pile interaction under seismic excitation

Nonlinear anisotropic finite element analysis of liquefiable tunnel–sand–pile interaction under seismic excitation

Deformation and Stress Analysis of Pile-Supported Immersed Tunnels under Seismic Loads

Mechanical Characteristics of Variable Cross‐Section Immersed Tunnels under Spatial Differential Settlement

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