Fiber reinforcement has been demonstrated to mitigate soil liquefaction, making it a promising approach for enhancing the seismic resilience of tunnels in liquefiable strata. This study investigates the seismic response of a tunnel embedded in a liquefiable foundation locally improved with carbon fibers (CFs). Consolidated undrained (CU), consolidated drained (CD), and undrained cyclic triaxial (UCT) tests were conducted to determine the optimal CFs parameters, identifying a fiber length of 10 mm and a volume content of 1 % as the most effective. A series of shake table tests were performed to evaluate the effects of CFs reinforcement on excess pore water pressure (EPWP), acceleration, displacement, and deformation characteristics of both the tunnel and surrounding soil. The results indicate that CFs reinforcement significantly alters soil-tunnel interaction dynamics. It effectively mitigates liquefaction by enhancing soil stability and slowing EPWP accumulation. Ground heave is reduced by 10 %, while tunnel uplift deformation decreases by 61 %, demonstrating the stabilizing effect of CFs on soil deformation. The fibers network interconnects soil particles, improving overall structural integrity. However, the increased shear strength and stiffness due to CFs reinforcement amplify acceleration responses and intensify soil-structure interaction, leading to more pronounced tunnel deformation compared to the unimproved case. Nevertheless, the maximum tunnel deformation remains within 3 mm (0.5 % of the tunnel diameter), posing no significant structural risk from the perspective of the experimental model. These findings provide valuable insights into the application of fibers reinforcement for improving tunnel stability in liquefiable foundations.

中文翻译：

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地震条件下纤维加固对砂土液化减缓及盾构隧道稳定性的影响研究

纤维加固已被证明可以减轻土壤液化，使其成为增强可液化地层中隧道抗震能力的一种很有前途的方法。本研究调查了嵌入碳纤维 （CF） 局部改进的可液化地基中的隧道的地震响应。进行固结不排水 （CU）、固结排水 （CD） 和不排水循环三轴 （UCT） 测试以确定最佳 CFs 参数，确定纤维长度为 10 mm 且体积含量为 1% 为最有效。进行了一系列振动台试验，以评估 CFs 加固对隧道和周围土体的超孔隙水压力 （EPWP）、加速度、位移和变形特性的影响。结果表明，CFs 加固显著改变了土体-隧道相互作用动力学。它通过增强土壤稳定性和减缓 EPWP 积累来有效减轻液化。地表隆起减少了 10 %，而隧道隆起变形减少了 61 %，证明了 CFs 对土体变形的稳定作用。纤维网络将土壤颗粒互连在一起，从而提高整体结构完整性。然而，由于 CFs 加固而增加的抗剪强度和刚度放大了加速度响应并加强了土体与结构的相互作用，与未改进的情况相比，导致隧道变形更明显。尽管如此，隧道的最大变形保持在 3 毫米（隧道直径的 0.5%）以内，从实验模型的角度来看，没有构成重大的结构风险。这些发现为纤维加固在提高可液化地基隧道稳定性中的应用提供了有价值的见解。