盾构隧道强震灾变的宏-细观并发多尺度方法

Tunnel structures are susceptible to receive irrecoverable damage in recent earthquakes. For shield tunnels, macro-scale dynamic response has a strong relationship with meso-scale dynamic evolution under strong earthquakes. However, traditional numerical simulation and model testing methods cannot be used to fully describe the macro-scale and meso-scale dynamic behaviors of shield tunnels, and thus effective research methods are urgently required for dynamic hazard simulation of shield tunnels under strong earthquakes. Based on the multidisciplinary subjects intersected by tunnel dynamics, earthquake engineering and multiscale science, a concurrent numerical multiscale method and a multiscale model testing method, are systematically presented, for shield tunnels subjected to strong earthquakes. Both the theoretical, numerical and testing techniques are used to conduct the research. Main contents of the proposal include: the equivalent theory of longitudinal stiffness of macro-scale and meso-scale models of shield tunnel is derived; energy functions and constrained relations are built up to connect macro-scale and meso-scale models smoothly, and the corresponding multiscale dynamic equations are derived, and the damage theory is introduced to realize the concurrent multiscale numerical simulation; a multiscale shaking table test method for shield tunnels is proposed on the basis of equivalent design of macro-scale and meso-scale models; and via the comparative validation between numerical simulation and model test, both the macro-scale dynamic responses and meso-scale damage mechanisms of shield tunnels under strong earthquakes are fully revealed. Further expected accomplishments include a seismic safety evaluation method for shield tunnels based on the defined damage and energy indexes. The research proposal will be beneficial to develop and improve seismic theories and methods of tunnels, and furthermore will provide scientific basis for seismic design of tunnel structures.

近年隧道震害频发，强震环境下盾构隧道的宏观动力响应与细观动态演化密切相关，但传统数值模拟和模型试验方法均难以全面反映结构在宏-细观不同尺度下的力学行为，缺乏强震灾变模拟的有效研究手段。本项目交叉融合隧道动力学、地震工程学及多尺度科学等学科，采用理论分析、数值模拟和模型试验相结合的研究方法，系统研究盾构隧道强震灾变的并发多尺度动力分析方法和多尺度模型试验方法。包括推导盾构隧道宏-细观模型纵向刚度等效化理论；建立宏-细观模型相关联的能量函数和约束关系，推导多尺度动力控制方程，引入损伤理论实现并发多尺度数值模拟；建立基于宏-细观模型等效设计的多尺度振动台模型试验方法；通过数值模拟和模型试验交叉验证，揭示强震下盾构隧道的宏观动力响应规律和细观损伤演化机理。项目预期将建立基于损伤指标和能量指标的盾构隧道抗震安全性评价方法。项目研究有助于发展和完善我国隧道抗震理论和方法，为隧道抗震设计提供科学依据。

历史震害表明，强震作用是造成隧道结构损坏的主要原因，但目前缺乏强震灾变模拟的有效研究手段。本项目针对盾构隧道结构特点，提出了面向盾构隧道强震灾变模拟的并发多尺度动力分析方法和多尺度模型试验方法。首先，推导出考虑环缝构造特征和横向刚度影响的盾构隧道纵向宏观等效刚度的理论解，揭示了止水衬垫厚度、管环厚径比和隧道横向刚度有效率等关键因素对盾构隧道纵向等效抗弯刚度的影响规律；其次，开发出盾构隧道强震非线性模拟的连续-离散多尺度动力耦合模型，依据能量传递原理推导出多尺度动力控制方程并数值程序化，分析结果表明该方法既可以从细观尺度上模拟结构易损区域的大变形破坏、倒塌机制，又能保证模拟过程中宏-细观模型之间受力的平衡、位移的协调以及能量的平滑过渡，有效解决了不同尺度域之间的动力耦合难题；另外，还提出了一种考虑键拉弯剪耦合效应的广义微极近场动力学模型，实现了任意动载作用下结构或岩体等准脆性材料非线性变形、裂纹扩展、断裂等连续-非连续全过程行为的准确模拟，为隧道结构强震灾变模拟提供了有效分析手段；再者，研发了盾构隧道宏-细观动力灾变演化全过程的多尺度振动台模型试验平台，建立了盾构隧道宏-细观多尺度物理模型等效设计原则，可兼顾隧道整体力学特征与接缝、螺栓等细部构造，提出以隧道结构-地层相对刚度比为控制指标的动力相似设计理论，解决了1g“重力失真”环境物理模型动力作用相似比匹配的难题；最后，基于模型试验和数值模拟交叉验证，分析了强震作用下盾构隧道宏观动力响应规律和细观渐进破坏过程，揭示出强震作用下盾构隧道结构宏-细观动力灾变机理。此外，基于规律认识，建立了面向盾构隧道结构抗震设计的简化分析方法，推导出行波效应下盾构隧道纵向地震响应的理论解，以及浅埋隧道在表面Rayleigh波作用下纵向地震响应的解析表达式，为隧道结构纵向抗震设计和分析提供了科学依据。