偏压荷载引起的隧道衬砌裂损机制及FRP网格快速加固方法研究

The Breakage caused by bias pressure which seriously affects the operation safety of the tunnel, is a common disease for lining. In order to overcome the shortcomings of the traditional strengthening methods on the inner surface and forming a rapidly strengthening method of FRP Grid, The GC (Grancrete Concrete) rapidly solidified matrix and the FRP grid will be used as binder and ribs respectively based on textile-reinforced concrete; With the similar test and cracking simulation technology of XEFM, the research on the breakage characteristic and mechanism of the tunnel lining under bias pressure will be conducted; On the basis, it is to carry out the similar experiment of lining strengthened by FRP gird, and propose the reasonable simulation method for lining reinforced by FRP grid based on the constitutive models of strengthening layer and bonding interface got by axial tensile and shear test respectively, and further the strengthening parameter optimization analysis will be conducted. According to the stress state of the cracks section, the strengthening theory of controlling the breakage by FRP grid will be established considering the effect of the secondary load. Based on the similar test, numerical simulation and theoretical analysis, it will reveal the strengthening mechanism and form the methodology of tunnel lining strengthened by FRP Grid. This work is of great social significance and engineering value to ensure long-term health service for tunnel lining.

偏压荷载造成的裂损是衬砌常见的病害，它严重威胁着隧道的运营安全。为突破衬砌内表面传统加固方法的不足，在纤维编织网增强混凝土的基础上，分别采用FRP网格和GC（Grancrete Concrete）快凝基体材料作为加强筋和粘结剂，形成FRP网格快速加固方法；采用相似试验和扩展有限元裂缝模拟技术，揭示偏压荷载引起的衬砌裂损特征及裂损机制；在此基础上，开展FRP网格加固偏压衬砌相似试验，开展加固层拉伸、粘结界面拉剪和压剪试验，建立加固层和粘结界面的本构模型，构建FRP网格加固偏压衬砌的合理数值方法并开展加固参数优化分析，进一步根据裂缝截面的受力状态，考虑二次受力，建立FRP网格加固裂损衬砌的增强理论。综合试验、数值和理论分析等手段，揭示FRP网格加固偏压衬砌各项力学性质的强化机制，形成偏压衬砌的FRP网格快速方法体系。研究成果对保证隧道衬砌的长期健康服役，具有重大的社会意义和工程应用价值。

裂损是运营隧道衬砌最常见的一种病害，偏压荷载是其产生的主要因素之一。项目开发了快凝早强基体材料，形成了FRP网格快速加固方法；通过相似试验和数值模拟，揭示了隧道衬砌在偏压荷载作用下的裂损机制，探明了FRP 网格快速加固方法抑制偏压衬砌裂损的作用机理，建立了FRP网格控制偏压衬砌正截面裂缝扩展的全过程计算理论。研究表明：快凝早强FRP网格快速加固方法在2小时内即可起到加固作用；偏压荷载作用下，偏压荷载作用中心处的衬砌内表面会产生一条张拉主裂缝，偏心距是控制其扩展特征的关键指标；随着偏压荷载作用范围的增大，裂缝截面偏心距降低，衬砌承载力和裂缝扩展速率降低；偏压衬砌内表面裂缝在扩展初期表现为深度上的发展，后转变为宽度上的发展，破坏后外观呈现为“Λ”型；FRP网格可以有效地抑制偏压衬砌裂缝的扩展；对于拱腰作用偏压荷载的衬砌加固，合理加固范围建议为偏压荷载作用中心的内表面45°范围内；采用FRP网格加固，偏压荷载作用范围越大，衬砌承载力提高越大、裂缝扩展速率及裂缝宽度降低越显著；随着FRP网格用量的提高，衬砌承载力提高、裂缝扩展速率降低，但是FRP网格利用率降低；前期受力历史造成加固层存在应力损失，且前期受力历史越大应力损失越大，因此随着前期受力历史的增大，FRP网格控制偏压衬砌裂损效果降低。研究结论可以有效指导隧道衬砌裂损控制，所形成的FRP网格快速加固方法不仅可以应用于隧道衬砌的加固，还可以应用于混凝土结构的应急抢险和长期加固，具有较为广泛的应用前景。