考虑接头时变行为的盾构隧道衬砌结构性能演化机理

With the development of the scientific research on structural behavior of segmental tunnel linings, it is gradually known that structural behavior is governed by the local behavior of the interfacial joints between neighboring segments. This conclusion was drawn basically based on short-term experimental investigations and numerical modelling without consideration of time-dependent behavior of the joints. The latter involves the creep of concrete under high compressive stresses, deterioration of the concrete, and corrosion of the interfacial bolts, due to the corrosive medium contained by groundwater. The aim of this project is to (i) study the time-dependent behavior of the joints in the perspective of their microstructures and materials and (ii) to illuminate the mechanism underlying the time-dependent behavior of the macroscopic structures governed by that of the joints. To this end, tunnel linings are treated at three scales. As for the scale of materials, a micromechanics-based multiscale model, for creep of concrete in corrosive medium, will be developed. Such a model will allow for illuminating the evolution law of the material properties of concrete under coupled long-term effects of loading, pore pressure, and corrosive medium. When it comes to the scale of the interfacial joints, combing the multiscale model for concrete and a classic model for corrosion of bolts, and carrying out theoretical analysis, a mechanical model for the joints will be developed. This model will permit describing the nonlinear relation between the relative rotation angle and the transmitted forces across the joints. The research will be continued with the scale of tunnel linings. Based on the state-space technique, a hybrid method for structural analysis of segmental tunnel linings, considering realistic behavior of the joints, will be developed. This method will help in clarifying the correlation between the structural failure and the state of the joints. Finally, a time-history analysis model for structural behavior of segmental tunnel linings will be delivered. The achievements of this project will be able to provide theoretical basis and practical methods for safety warning of segmental tunnel linings under long-term operation.

随着对盾构隧道衬砌结构研究的不断深入，人们逐步认识到接头是控制盾构隧道衬砌结构性能的关键部位。然而，目前的认识普遍来源于对短期宏观试验现象的分析和不考虑接头时变行为的计算模拟。接头性能的时变效应主要包括高应力作用下混凝土的徐变，地下侵蚀水环境下的混凝土性能劣化以及螺栓锈蚀。本项目拟从微观上研究接头性能的时变效应，从机理上揭示接头影响宏观结构性能的作用机制。在材料尺度，基于细观力学建立侵蚀环境下混凝土的徐变多尺度模型，探明接头混凝土在荷载、孔隙水压力和侵蚀性介质持续耦合作用下的性能演化规律；在接头尺度，结合混凝土的徐变多尺度模型，引入经典的螺栓锈蚀模型，通过理论分析建立接头的非线性力学模型；在衬砌结构尺度，基于状态空间法开发一种考虑接头真实性能的结构混合分析方法，明确结构失效与接头状态的内在关联，形成结构性能时程分析模型。项目研究成果将为长期运营隧道结构的安全预警提供理论依据和实用计算方法。

盾构法是一种机械化程度极高的隧道施工方法，在高速发展的城市轨道交通建设中得到广泛的应用。盾构隧道的设计寿命长达100年。在此期间，衬砌结构性能不断演化，一旦发生损坏，可能造成城市交通系统的瘫痪和恶劣的社会影响。本研究围绕盾构隧道结构安全问题，开展了如下探究工作：.（1）采用多尺度模拟方法，建立了盾构隧道结构混凝土材料长期性能本构模型，通过对比结构多尺度分析结果、传统结构分析结果以及隧道结构足尺试验结果，揭示了混凝土材料多尺度分析对于盾构隧道结构长期服役性能评估的重要价值。.（2）基于混合分析理念，将监测数据和机理模型相结合，考虑接头非线性行为，建立了盾构隧道结构变形在长期服役过程中的发展演化模型，为盾构隧道结构服役状态的快速识别提供了工具。.（3）提出超过使用极限状态的盾构隧道变形反演混合分析方法，为盾构隧道结构维护措施的选择提供了参考依据。.（4）针对受损严重和临时盾构隧道结构，发展了大盾构复推重建工法，为了验证这种工法的可行性，提出了一种模型试验设计原理和方法，试验结果为这种工法的首次实施提供了技术支撑。.本研究成果为衬砌结构全寿命周期内的性能预测和安全维护提供理论基础和技术支撑。实现衬砌结构全寿命周期内的性能预测，有助于精细化设计盾构隧道衬砌结构。一方面，有望在确保安全的前提下，降低建设成本;另一方面，根据结构性能预测信息，科学合理的提出基于“主动维护”理念的维护方案和维护时机，减少事故的发生，降低结构的安全维护费用。此外，本研究支撑的大盾构复推小盾构工法为废弃隧道所占据地下空间的再利用提供了新方法。.