火灾时隧道衬砌结构内温度场分布规律试验

借助火灾试验,对衬砌结构内温度场随时间的变化规律、温度场沿厚度的分布规律以及不同边界条件对温度场的影响进行了研究.试验中,衬砌结构混凝土等级为C50,升温曲线采用HC曲线,升温及恒温持续时间约60min.试验结果表明衬砌结构内各点的升温曲线在100～115℃附近会出现一个明显的恒温平台,且距受火面越远,温度平台出现的时间越晚,持续的时间越长,这反映了混凝土内水分的蒸发吸热过程.在试验升温、恒温及降温全过程中,衬砌结构内温度场沿厚度方向的分布满足指数衰减规律.同时,相对裸露于大气中的结构,由于周围岩土体的吸热,衬砌结构中各点的温度要偏低,且越靠近边界,偏低量越大.

Experimental Study on Temperature Field Distribution of Tunnel Lining Structure in Fire Accidents

An experimental study was made of the temperature field distributions of tunnel lining structure under high temperature.The content of research includes variation of temperature of lining structure with time,temperature field distribution along thickness of lining structure and effect of boundary condition on temperature field distribution.HC curve with about 60 min period of duration of heating and testing lining segments casted by C50 concrete are employed in the experiments.The results indicate that due to water evaporation of concrete,temperature of lining structure stops increasing when its temperature reaches to 100~115 ℃.With the increase of distance from the heating face of the lining structure,the phenomenon of stopping increasing temperature occurs later and the period of duration increases.Furthermore,the temperature field distribution along the thickness of lining structure can be described by exponential decay curve.Finally,due to heat absorption by surrounding soil the temperature of lining structure is lower than the ones exposed to atmosphere,and the closer to the boundary,teh larger the difference.