施工和运营期高温对盾构隧道复合管片衬砌力学性能的影响及防控措施研究

High temperature during construction and operation period has direct influence on the mechanical properties, cost and safety of composite segment. However, the stress state and failure mechanism of composite segment under high temperature are not clarified, and the analyzed method, experimental index and testing approach are not unified either. By means of modeling experiment, numerical simulation and theoretical analysis, the following key issues of composite segmental linings under high temperature will be solved: a) The residual stress and deformation of thin-walled rectangular steel tube will be illustrated by magnetic measurement and video method. And considering welding defect, the thermo-elastic-plastic model will be established to investigate the effect of welding temperature on the mechanical properties, dimension accuracy and assembling precision of composite segment. b) The infrared thermal imager and thermocouple will be applied to present the fire scenario, and the varying rules of internal temperature with the change of time and position will also be analyzed. The mapping relationships between test parameters and calculation parameters will be built to reveal the mechanical properties and failure mode of composite segment, joint and lining structure under fire. c) According to the above results, the static loading method for simulating high temperature load and the rationality of equivalent criteria for damaged material will be proved. Meanwhile, the prevention measures will be proposed to control the influences of high temperature for composite segmental lining. The results in this study will enrich the theoretical solution to thermo-mechanical problem of tunnel lining, and will provide theoretical basis for the design and construction of composite segmental linings under high temperature. All of these have guiding significance for the prevention and control of tunnel fire.

施工和运营期高温会直接影响盾构隧道复合管片衬砌的力学性能、成本和安全性，而目前研究仍存在受力情况和破坏机理不明确，分析方法、性能试验标准和试验方法不统一的问题。本项目拟采用模型试验、数值模拟、理论分析等手段解决复合管片衬砌高温影响分析的关键科学问题：①采用磁测和视频法，阐明焊接温度下的残余应力和变形规律，构建考虑焊接缺陷的热弹塑性数值模型，揭示焊接温度对复合管片力学性能、尺寸精度和拼装精度的影响；②采用红外热像法和热电偶法阐明火灾场景和结构内部温度随时间和位置的变化规律，建立试验参数与计算参数之间的映射关系，揭示火灾下复合管片、接头、衬砌结构体系的力学特性和破坏模式；③基于上述成果验证模拟高温荷载的静力加载方法和损伤材料等效准则的有效性，提出复合管片衬砌防控高温影响的措施。研究成果可丰富隧道衬砌热力问题求解的理论体系，为高温下复合管片衬砌施工和设计提供理论基础，对防控隧道火灾具有指导意义。

本项目主要研究包括：.针对施工期高温下矩形钢管力学行为与表征，采用多场耦合方法，从焊接方式、焊接顺序和焊接间隔时间三方面分析焊接布局对结构残余应力的影响，共设置了16组焊接工况分析结构温度、残余应力和残余变形随焊接布局变化的规律；在此基础上提出了将大体量焊缝同时焊接的优化方案，分析了焊接残余应力对于结构的削弱作用。.针对施工期高温和混凝土压注对复合管片力学性能的影响研究，建立了剪力键焊接动态模拟数值模型，分析了特征点的应力及变形规律；建立了混凝土浇筑模型，分析了浇筑完成后的板件应力变形分析及不同钢板厚度下的敏感性分析；通过考虑焊接初始缺陷的混凝土浇筑分析和剪力键拉拔性能分析，得出了压注过程中混凝土对板材及剪力键性能的影响规律。.针对运营期火灾高温对复合管片和接头力学性能的影响研究，建立了火灾高温下复合管片、接头和衬砌环的热弹塑性数值模型，并采用RABT火灾曲线，分析了火灾高温下复合管片、接头和衬砌环的温度场分布、变形规律、承载力和损伤模式。.针对运营期火灾高温对复合管片衬砌体系力学性能影响研究，建立了火灾高温下矩形钢管与混凝土接触界面热传递分析、复合管片衬砌防水性能退化分析、复合管片衬砌环受火分析的精细化数值模型，采用温度与荷载顺序耦合的方式，定量分析火灾高温下钢管与混凝土接触界面温度不连续性规律和火灾对复合管片衬砌防水性能的影响，构建火灾高温下复合管片衬砌环内力场重分布的计算公式。.通过理论分析、数值模拟和试验等多方面研究，完成了对施工和运营期高温下复合管片、接头和复合管片衬砌环受力和变形的重演分析，推导并验证了焊接移动热源模型和火灾高温下内力场公式，形成了复合管片焊接残余变形评价系统。通过数值模型分析与模型试验验证表明，上述成果可以为施工和运营期高温对盾构隧道复合管片衬砌影响研究提供理论指导，完善了盾构隧道复合管片的设计理论体系和试验方法。