Structural design and mechanical responses of closely spaced super-span double tunnels in strongly weathered tuff strata

He, Jiaxin; He, Shunping; Liu, Xiabing; Zheng, Jinlei

doi:10.1007/s11709-022-0824-2

Cited by 3 publications

(2 citation statements)

References 21 publications

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“…Due to the late start of single-hole four-lane highway tunnels, research in the field of tunnel engineering on large-span highway tunnels mainly focuses on single-hole threelane highway tunnels and double-track railway tunnels [8][9][10], while there are limited studies on single-hole four-lane super large-span highway tunnels. Previous research on large-span highway tunnels has mainly focused on construction methods [11,12], support parameters [13][14][15], and stability control of surrounding rock [16][17][18] during construction. Nevertheless, there has been less attention paid to the stress properties of the secondary lining of large-span highway tunnels, and related research has mainly focused on load effects.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behavior of Secondary Lining in Super Large-Span Tunnels Considering Temperature Effects

Dong,

Luo,

Chen

et al. 2024

Symmetry

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Temperature stress has a significant impact on the structural stress of (super) large-span tunnel lining, which can easily lead to structural fatigue damage and premature cracking. With the increasing scale and quantity of super large-span tunnels, the issue of temperature stress in secondary lining has attracted widespread attention. Previous studies have paid little attention to the influence of temperature stress on the structural internal forces of ordinary small–medium-span tunnels, but this influence cannot be ignored for super large-span tunnels. We take the Letuan Tunnel (a double-hole eight-lane tunnel) of the Binzhou-Laiwu expressway renovation and expansion project in Shandong Province as a case study and analyze the mechanical response of the secondary lining through on-site measurement. Moreover, a numerical simulation was conducted to evaluate the effects of self-weight and temperature stress on the secondary lining of the case tunnel. The results indicate that: the stress of the secondary lining concrete and steel bars is greatly affected by seasonal temperature changes. The compressive stress of the concrete and steel bars is significantly greater in summer than in winter, and the tensile stress is greater in winter than in summer. Furthermore, multiple measurement points have shown a phenomenon of transition between tensile and compressive stress states. The stress of concrete and steel bars fluctuates periodically with a sine function over time, with a fluctuation period of one year. The structural stress increases with the increase of summer temperature and decreases with the decrease of winter temperature. The fluctuation amplitude of stress in the inner side of the lining concrete and steel bars is greater than that on the outer side. Among them, the stress amplitudes of the inner and outer sides of the concrete are between 0.77–1.75 MPa and 0.44–1.07 MPa, respectively, and the stress amplitudes of the inner and outer steel bars are between 5–31 MPa and 7–13 MPa, respectively. The safety factors in summer are lower than those in winter. The minimum safety factors for secondary lining in summer and winter are 3.4 and 4.6, respectively, which can meet the safety requirements for service. The average axial forces of the secondary lining under the coupling effects of self-weight and temperature in winter and summer are 528 MPa and 563 MPa, respectively, which are significantly greater than the combined axial forces under their individual effects. The bending moment distribution of the secondary lining at the tunnel vault, inverted arch, wall spring and other positions under the coupling effect of self-weight and temperature is different from or even opposite to the bending moment superposition result under the two individual actions. The achieved results reveal that the influence of temperature stress on the service performance of the lining structure cannot be ignored, and the research results can provide useful reference for similar tunnels and related studies.

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Section: Introductionmentioning

confidence: 99%

Mechanical Behavior of Secondary Lining in Super Large-Span Tunnels Considering Temperature Effects

Dong,

Luo,

Chen

et al. 2024

Symmetry

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“…The subsection excavation methods have been widely applied in practical engineering projects. These methods include the double-side-drift method (DSD), the center diaphragm method (CD) and the cross diaphragm method (CRD) [7,8].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Response and Stability Optimization of Shallow-Buried Tunnel Excavation Method Conversion Process Based on Numerical Investigation

Pan,

Zhou,

Jiang

2024

Buildings

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Different excavation methods lead to substantial changes in the relaxation zone of the surrounding rock. The stress characteristics of the support structure become more complex during the process of excavation method conversion. It is essential to design a well-considered construction plan to minimize the disruptions caused by excavation method conversion. This work takes a tunnel in Jiangsu Province, China, as the engineering background and establishes a numerical model for the conversion from the double-side-drift method to the three-bench method. Based on a numerical investigation, this study analyzed the deformation of surrounding rock and the stress state of the support structure during the excavation method conversion. The results showed that excavation method conversion can accelerate the deformation rate of the surrounding rock, causing the support structure to bear greater pressure. This leads to a significant increase in the circumferential stress at the junction of two excavation methods. Setting up a reinforced area during the process of excavation method conversion can improve the stress state of the support structure. Finally, an analysis of the parameters of the reinforced area was conducted, and a reasonable construction plan was proposed. This study can provide guidance for subsequent construction projects.

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Investigating the Mechanical Responses and Construction Optimization for Shallow Super-Large Span Tunnels in Weathered Tuff Stratum Based on Field Monitoring and Flac3D Modeling

He,

Liu

et al. 2023

Int J Civ Eng

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Structural design and mechanical responses of closely spaced super-span double tunnels in strongly weathered tuff strata

Cited by 3 publications

References 21 publications

Mechanical Behavior of Secondary Lining in Super Large-Span Tunnels Considering Temperature Effects

Mechanical Behavior of Secondary Lining in Super Large-Span Tunnels Considering Temperature Effects

Mechanical Response and Stability Optimization of Shallow-Buried Tunnel Excavation Method Conversion Process Based on Numerical Investigation

Investigating the Mechanical Responses and Construction Optimization for Shallow Super-Large Span Tunnels in Weathered Tuff Stratum Based on Field Monitoring and Flac3D Modeling

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