火灾作用下隧道结构力学响应及稳定性分析

Stability Assessment and Mechanics Response of Tunnels Subjected to Fire Load

隧道火灾会引起衬砌结构发生高温损伤,威胁隧道运营安全。从材料微观物理化学变化出发,研究了混凝土中水化物的热分解和骨料力学性能的高温劣化过程,揭示了其在火灾等高温作用下宏观力学性能的劣化机理,建立了相应的高温损伤分析模型,在传统模型仅能考虑温度大小影响的基础上进一步考虑了温度持续时间对材料力学性能劣化的影响。以上海某软土地区盾构隧道为算例,分析了不同火灾持续时间作用下衬砌结构的高温损伤过程,得到了衬砌结构在温度和力学荷载共同作用下的应力状态、围岩变形及隧道稳定性的变化规律,为隧道衬砌结构的防火设计及灾后评估与修复提供参考。

Tunnel fire can lead to damage of lining structures,and endangers safety of tunnels.Based on microscopic physical and chemical changes of inner components at high temperature,the thermal decomposition process of hydrates and thermal damage process of aggregate at high temperature are studied,and the degradation mechanisms of concrete at high temperature are revealed,then a thermal damage model is proposed.The model not only can consider the influence of temperature as traditional models,but also can take into account the influence of temperature duration.Based on the model,the lining structure damage of a shield tunnel in soft soil is studied.The change law of mechanics response,deformation and stability of the tunnel under the load of temperature and force is provide,which can be used as a reference for fire safety design and assessment of concrete structures after fire.