火灾高温下隧道衬砌混凝土爆裂及力学行为研究

The safety of tunnel exposed to fire is one of the key problems of tunnel safety. And the mechanical properties of concrete for tunnel lining at high temperatures provide a basis for the study of safety for tunnel in fire. .Firstly, the spalling protection will be investigated by the spalling test of concrete (self-compacting concrete) for tunnel lining at high temperatures in this study. The occurrence probability of spalling will be evaluated quantitatively and the model of spalling will be established based on the damage process of microstructure of concrete at high temperatures. Secondly, the deformation properties of self-compacting concrete will be investigated by tests, such as transient strain, short-term creep strain at high temperatures and instantaneous stress-related strain. Thirdly, the multiscale chemo-thermo-mechanical coupling models for thermal strain and elastic modulus of self-compacting concrete under high temperatures will be established based on the damage mechanics theory and the evolution of microstructure of self-compacting concrete. Finally, the numerical simulation and theory analysis of tunnel linning will be done in order to verify the above multiscale chemo-thermo-mechanical coupling model of thermal strain. .The spalling and mechanical properties of concrete for tunnel lining at high temperatures will be described exactly in this study, which provide a basis for investigating the fire behavior of tunnels and concrete structures.

隧道结构的火灾安全性是其安全性能研究的重要课题，而衬砌材料混凝土高温力学性能的建立是进行隧道结构火灾安全分析的基础。.本项目拟通过火灾高温下隧道衬砌混凝土（自密实混凝土）的爆裂试验，探讨隧道结构混凝土的爆裂控制措施，并且结合混凝土微观结构的损伤演化过程，定量的评价隧道结构混凝土的高温爆裂机率，建立混凝土的高温爆裂模型；进而基于通过混凝土高温变形试验得到的瞬态应变、短期高温徐变、应力产生的即时应变等高温应变，以及损伤力学理论和混凝土微观结构的演化模型，构建能够考虑高温下混凝土微观结构演变的热-力-化学耦合效应的多尺度变形模型；在此基础上，通过理论分析和数值模拟，对上述模型进行验证。.项目研究旨在更为精细的描述隧道衬砌混凝土高温爆裂及力学性能的损伤规律，为探明隧道结构高温行为的演化特征和分析混凝土结构的高温性能提供依据和基础。

针对隧道火灾升温速率快，隧道内环境湿度大等特点，借助高温试验和理论分析等手段，分析了隧道衬砌结构混凝土的火灾高温爆裂特点，深入探讨了高温爆裂的影响因素，结合混凝土微观结构的高温损失演化过程，评价隧道衬砌混凝土的高温爆裂程度，研究了爆裂中出现的重要参数，如爆裂速率、爆裂能量等，建立了适用于隧道衬砌混凝土的高温爆裂机理。得到了高温下隧道衬砌混凝土的抗压强度、弹性模量、应力-应变曲线等变化规律，建立了适用于隧道高温环境的计算模型。研究了高温下隧道衬砌混凝土的变形规律，探讨了其影响因素，给出了相应的计算模型。基于损伤力学和复合材料力学理论，建立了适用于隧道火灾场景的混凝土化学-热-力损伤模型。项目成果为解决隧道衬砌混凝土火灾高温性能及安全性问题提供了一定的理论基础。