微胶囊自防火隧道混凝土衬砌高温力学行为研究

As one of the frequent disasters threating the safety of tunnel operation, tunnel fire damages the lining structure seriously and lowers the stability. According to insufficient of current tunnel lining fire protection and enlighten by the idea of microcapsule self-healing, this research proposes a new fire protection method for the tunnel lining based on microcapsule self-healing theory and fiber reinforced concrete research that have been developed. By the means of fire test, theoretical analysis and numerical simulation, study on the function mechanism, heat conduction properties, temperature field distribution and mechanical properties of microcapsule self-fire protected concretes under high temperature induced by fire will be deeply carried out. Further, quantitative analysis models and method for dominate parameters, temperature field propagation and distribution and mechanical properties degradation of microcapsule self-fire protected concretes are proposed aiming at the particularity of tunnel environment and key issues for the self-fire protected of tunnel lining structure. Finally, novel method and mechanical behavior computational theory for microcapsule self-fire protected concretes will be established and will also be provided as the basic theories. With the active fire protection triggered by elevated temperature induced by tunnel fire, above research will fully develop the potential anti-fire ability of the tunnel structure and implement the structure loss of spalling and heat damage. The guarantee of fire prevention and work ability will solve the fire safety issues of undersea tunnels lining structures in complicated environment.

火灾是威胁隧道安全运营的主要灾害之一，火灾高温会对衬砌结构产生严重的损伤和破坏，降低其安全性。针对现有隧道衬砌防火方法的不足，本项目借鉴微胶囊自修复思想，并在对前期开展的微胶囊自修复混凝土与纤维混凝土研究工作的继承与发展的基础上，提出了微胶囊自防火隧道混凝土衬砌的新方法。拟借助火灾试验、理论分析和数值计算等手段，深入研究火灾高温下微胶囊自防火混凝土衬砌的作用机理、热传导特性、温度场分布特征与力学特性，进而建立微胶囊自防火混凝土衬砌的控制参数、温度场传播分布、力学性能退化规律的定量分析计算模型与方法；并以此为基础，最终建立微胶囊自防火隧道混凝土衬砌新方法及其配套的力学行为计算理论，以充分发挥隧道衬砌结构自身的防火能力，实现防爆裂与隔热的同步、防火与承载的协同作用以及火灾热触发下的自动防火，为解决复杂环境下地铁及越江跨海隧道衬砌结构的防火安全问题提供理论基础和新技术支撑。

混凝土结构在高温下往往出现结构性能劣化，这对于地下结构的承载力和可靠性造成了极大的威胁。针对被动式防火方法的不足，本项目提出了基于微胶囊自防火混凝土的主动式抗火新方法，通过在混凝土结构保护层中掺加自防火微胶囊，在不改变结构尺寸、不增加结构额外荷载的条件下，通过“吸热+散热+隔热”的方式，充分发挥隧道衬砌结构自身的防火能力，实现火灾热触发下的结构主动防火模式。本项目提出了以三聚氰胺、聚磷酸铵和季戊四醇为膨胀型阻燃剂的自防火微胶囊制备方法，结合高温下红外光谱分析等多种材料表征方法，深入地分析了膨胀型阻燃剂在高温下的发泡过程及其产物，对自防火微胶囊混凝土的作用机理进行了深入的研究；在此基础上，针对混凝土的微观结构及微观成份组成，在水泥浆体层次、混凝土层次及混杂纤维混凝土层次等多个层次上，建立了描述混杂纤维混凝土在高温下力学损伤特性的多尺度计算模型；并通过数值模拟方法，在结构尺度探究了混杂纤维混凝土高温下的力学特征。