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As transportation networks continue to expand into mountainous regions with high seismic activity, ensuring the seismic safety of tunnels crossing active faults has become increasingly crucial. This study aimed to enhance our understanding of the impact of fault zones on the seismic behavior of tunnels and to provide optimized seismic design recommendations through a comprehensive experimental and numerical investigation. The focus of this research is the Xiangyangshan Highway Tunnel in China, which intersects a significant longitudinal fault. Large-scale shake table tests were performed on 1:100 scale physical models of the tunnel to analyze the seismic responses under various ground motion excitations. Detailed three-dimensional finite difference models were developed in FLAC3D and calibrated based on the shake table results. The tests indicated that strains, earth pressures, and accelerations experience localized amplification within 10–20 m of the fault interface compared to undisturbed ground sections. Common seismic mitigation measures, such as rock grouting, seismic joints, and shock absorption layers, were observed to effectively reduce the amplified seismic demands. Grouting, in particular, led to an average reduction of up to 56.3% in circumferential strain and 38.5% in earth pressure. It was concluded that 6 m thick grouted zones and 20 cm thick rubber interlayers between tunnel lining shells provide optimal structural reinforcement against the effects of fault zones. This study provides valuable insights for improving the seismic resilience of underground transportation corridors in seismically active regions. [ABSTRACT FROM AUTHOR]

As transportation networks continue to expand into mountainous regions with high seismic activity, ensuring the seismic safety of tunnels crossing active faults has become increasingly crucial. This study aimed to enhance our understanding of the impact of fault zones on the seismic behavior of tunnels and to provide optimized seismic design recommendations through a comprehensive experimental and numerical investigation. The focus of this research is the Xiangyangshan Highway Tunnel in China, which intersects a significant longitudinal fault. Large-scale shake table tests were performed on 1:100 scale physical models of the tunnel to analyze the seismic responses under various ground motion excitations. Detailed three-dimensional finite difference models were developed in FLAC3D and calibrated based on the shake table results. The tests indicated that strains, earth pressures, and accelerations experience localized amplification within 10–20 m of the fault interface compared to undisturbed ground sections. Common seismic mitigation measures, such as rock grouting, seismic joints, and shock absorption layers, were observed to effectively reduce the amplified seismic demands. Grouting, in particular, led to an average reduction of up to 56.3% in circumferential strain and 38.5% in earth pressure. It was concluded that 6 m thick grouted zones and 20 cm thick rubber interlayers between tunnel lining shells provide optimal structural reinforcement against the effects of fault zones. This study provides valuable insights for improving the seismic resilience of underground transportation corridors in seismically active regions.

In order to apply damping technology to complex interaction system, a two-dimensional finite element-infinite element coupling model of tunnel-soil-surface building interaction system was established by ABAQUS. By analyzing the acceleration, displacement and stress response of key points of tunnel and surface buildings, the influence of the thickness and buried depth of the shock absorption layer on the damping effect of the system is studied when tunnel shock absorption layer (or foundation shock absorption layer) is set separately. And a combined shock absorption system is proposed for the complex interaction system, and the primary and secondary relationship of different factors on the damping effect is studied by orthogonal experiment. The results showed that: (1) setting up a tunnel shock absorption layer can significantly reduce the maximum principal stress of the tunnel and the acceleration of the surface building; (2) when the buried depth of the foundation shock absorption layer was 0 m, the damping effect was the best, which can significantly reduce the acceleration and relative displacement of the surface building; (3) The combined shock absorption system can achieve good damping effect under different seismic waves excitation and its damping effect was better than single shock absorption layer system.

Shock absorption layer is an effective measure to decrease damage of tunnels under earthquake. According to previous work, the smaller stiffness of damping material, the better damping effect of the tunnel. In order to meet the actual engineering requirements, the shock absorption layer is applied to the upper part of tunnels (not including the invert), which is called a local shock absorption layer. This study is to analyze the damping effect of different types of local shock absorption layers based on the dynamic nonlinear time-history numerical analysis. Six real ground motions with different dominant frequencies are selected, their peak ground accelerations (PGA) are set to 0.2 g, 0.4 g, 0.6 g, and 0.8 g, respectively. The damage index and total dissipated energy of secondary lining, and equivalent plastic strain of surrounding rock are used as indicators to reflect the damping performance of the local shock absorption layer. Numerical results highlight that the damping performance with double local shock absorption layer is the best, and the damping performance of shock absorption layer under large earthquake is better than that under small earthquake. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)