大跨度偏压隧道受火损伤分析

为探明火灾对大跨度偏压隧道造成的不利影响，依托贵州省某公路隧道工程，基于ANSYS有限元软件分析不同埋深及偏压条件下大跨度隧道结构的最大损伤和相对温度损伤变化规律，并对其温度场分布和应力分布规律进行总结。结果表明:衬砌高温损伤约60 mm，温度影响深度约300 mm，内部温升过程逐渐由曲线变化转变为直线变化；最大损伤深度随偏压角度增加近似呈指数增长变化，而相对温度损伤略有减小，当偏压角度较大时，火灾将成为隧道破坏的诱导因素而非直接因素；最大损伤深度与偏压隧道埋深近似呈抛物线变化，火灾对偏压隧道影响显著，必须采取有效预防措施；随着受火时间的增加，临火侧衬砌混凝土在热膨胀及围岩约束作用下，压应力快速增加，存在较大的压溃风险。

Fire damage analysis of long span unsymmetrical loading tunnel

To investigate the adverse effect of fire on the long span unsymmetrical loading tunnel,based on a highway tunnel project in Guizhou Province,the change laws of the maximum damage and relative temperature damage of the long span tunnel structure under different buried depths and unsymmetrical loading conditions were analyzed based on ANSYS finite element software,and the distribution laws of temperature field and stress were summarized.The results showed that the high temperature damage of the lining was about 60 mm,the temperature influence depth was about 300 mm,and the internal temperature rise process gradually changed from curve change to linear change.The maximum damage depth changed approximately as exponential growth with the increase of the unsymmetrical loading angle,while the relative temperature damage decreased slightly.When the unsymmetrical loading angle was large,the fire would become the inducing factor of the tunnel failure rather than the direct factor.The maximum damage depth and the buried depth of the unsymmetrical loading tunnel would change approximately as the parabolic change,and the fire had significant influence on the unsymmetrical loading tunnel,so the effective prevention measures must be taken.With the increase of fire action time,the compressive stress of the lining concrete adjacent to the fire side increases rapidly under the effect of thermal expansion and surrounding rock constraints,and there is a greater risk of collapse.