盾构隧道施工影响下框架建筑物变形损伤机制及非概率可靠性研究

Due to the interaction effects among the multiple influential factors from the sides of tunneling, ground and building, and the uncertainties of the computational parameters, the assessment of framed building damage and reliability was significantly restricted. Based on numerical simulation and similar model test, this project will first investigate the working mechanism of the tunneling-ground-building interaction and the transmission law of stress-strain at the interface between the ground and the framed building. A further development on the numerical model will carry out to simulate the the stiffness degradation of the framed building due to the occurrence of crack and damage, with which the effects of the change in relative soil-structure stiffness on the growth of building deformation and damage can be clarified. As a results, the target indicators and their critical values for characterizing the building deformation and damage will be determined. Moreover, the uncertainties of the parameters related to the shield tunnel construction, material and model properties, which are regarded as basic random variables, will be considered base on random set theory. Then, non-probabilistic analysis will be carried out based on random set finite element method, and the upper and lower bounds of the discrete cumulative probability distribution function and the ranges of most likely values of the target indicators will be derived. Furthermore, a framework for non-probabilistic reliability analysis of framed building subject to shield tunneling will be proposed, and the applicability of the method will be verified by the result from the similar model test and case studies. This study will promote the understanding of the deformation and damage behavior of building subject to nearby shield tunneling, and it is significantly essential in protecting the safety of tunneling and the adjacent buildings.

由于隧道施工、地层、建筑物多方面因素耦合影响和计算参数的不确定性，框架建筑物变形损伤及可靠性的评定存在很大的局限性。本项目首先通过数值模拟和相似模型试验研究盾构隧道施工-地层-框架建筑物的相互作用机理，阐明土-结构物界面应力应变传递规律；通过进一步建立框架建筑物裂损后刚度弱化的数值计算模型，分析地层-建筑物相对刚度变化对框架建筑物变形损伤发展机制的影响，明确框架建筑物变形损伤表征指标及临界值。在此基础上，基于随机集理论表征隧道施工、材料性能和模型参数的不确定性，建立随机集有限元的非概率可靠性分析模型，确定建筑物变形损伤表征指标的离散累积概率分布函数上下限和最有可能值域，形成盾构隧道施工影响下框架建筑物变形损伤非概率可靠性评定方法，并利用模型试验结果和实例数据验证方法的有效性。本项目可提高对隧道施工影响下邻近建筑物变形损伤行为的认识，对于保证城市盾构隧道施工及邻近建筑物的安全具有重要意义。

城市地下隧道施工诱发邻近建筑物变形与损伤涉及多因素的耦合作用，系统参数的不确定性、地层变形的刚度非线性及建筑结构复杂特征显著影响其安全与可靠性评定。本项目针对盾构隧道施工影响下框架建筑物变形损伤机制及安全性评定方面的关键问题，系统研究了建筑物自重与刚度对地层初始应力和初始刚度分布状态的影响规律，分析了隧道非均匀收敛变形模式对隧道施工引起地层变形的影响，揭示了隧道施工-地层-框架建筑物之间的非线性相互作用机理，通过阐明体系中不连续界面之间的变形传递规律，厘清了建筑物刚度分布特征及结构裂损后的刚度弱化对变形损伤发展趋势影响及其演化特征；建立了隧道施工-地层-框架建筑物相互作用精准化数值模型，分析了具有不同填充形式的独立浅基础框架建筑物对隧道施工引起地层位移变形响应特征，明确了不同工况特征下框架建筑物的变形损伤响应差异及演化特征；通过提出基于剪切畸变、水平应变和累积裂缝宽度的建筑物变形损伤状态综合评价指标，基于随机集理论考虑隧道施工参数、岩土与建筑材料参数的不确定性，采用扩展有限元方法模拟建筑物变形开裂特征，建立了随机集理论-扩展有限元耦合的非概率可靠性分析方法（RS-XFEM），可获得建筑物损伤变形的离散累积概率分布区间，进而通过优化拟合确定框架建筑物变形损伤的最有可能值域；在RS-XFEM分析框架下对建筑物受力变形特征规律进行了可靠性分析，结论表明该分析方法与现场实测数据具有很好的一致性，形成了盾构隧道施工影响下框架建筑物变形与损伤量化评定与可靠性分析方法。项目成果可为规避城市盾构隧道施工引发的邻近建筑物安全事故提供理论依据，提升人们对城市地下与地面建筑相互作用的安全性认识。

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