为研究装配式复合型材加固法对盾构隧道管片抗弯承载能力和变形能力的提升效果，采用一种基于外包玄武岩纤维单向布、钢管复合成型，并在钢管空腔内灌注管道压浆料的盾构隧道管片加固方法对北京市某地铁使用的盾构隧道管片进行加固。通过开展四点弯曲加载试验，对加固前后的管片进行系统对比分析，揭示加固措施对管片破坏模式、弯曲性能和应变分布特征的影响。进一步提出极限破坏判据，并结合试验现象与应变数据对加固机理进行剖析。试验结果表明： 1）加固前管片在加载过程中呈现以底部环向裂缝为主的垂直贯通破坏，而加固后管片表现为由中部向加载点发展的斜裂缝模式，破坏形态发生显著改变； 2）装配式复合型材加固后的管片通过外部约束、界面粘结和内部高强灌浆料三重机制使极限承载能力由523 kN提升至927 kN，提升幅度达77.2%； 3）加固管片底部应变曲线在弹性阶段差异不超过5%，说明装配式复合型材与混凝土之间变形协调性良好，具备较强的协同受力能力。
To evaluate improvements in the flexural capacity and deformation behavior of shield tunnel segments reinforced with prefabricated composite materials, a repair method that combines externally bonded basalt fiber unidirectional fabric with steel pipes is utilized. The segments are internally filled with prestressed grouting material. This reinforcement technique is implemented on shield tunnel segments from a metro project in Beijing, China. Four-point flexural tests are conducted to systematically compare the behavior of shield tunnel segments before and after reinforcement. The results elucidates the impact of the composite strengthening approach on failure mechanisms, flexural capacity, and strain distribution profiles. Based on the experimental findings and strain distribution data, an ultimate failure criterion is proposed, and the reinforcement mechanism is interpreted through a comprehensive analysis of the structural response. The experimental results indicate that: (1) Prior to reinforcement, the segment exhibits vertical through-cracks dominated by circumferential fractures at the bottom during loading, whereas after reinforcement, the failure mode shifts significantly to diagonal cracking initiated from the mid-span toward the loading points. (2) The ultimate bearing capacity of the segments strengthened with prefabricated composite profiles increases from 523 to 927 kN by 77.2% through the triple mechanism of external restraint, interface bonding, and internal prestressed grouting. (3) The strain curves at the bottom of the reinforced segments show adeviation of less than 5% from the unreinforced ones in the elastic stage, indicating strong deformation compatibility between the composite material and the concrete, and excellent synergistic load-bearing performance.
