火灾下隧道混凝土高温损伤现场试验研究

Study of field test on high temperature damage of tunnel lining concrete under fire

为研究火灾高温作用对隧道衬砌混凝土损伤的影响程度,在某公路隧道一横通道内开展现场火灾试验,测量内容包括火灾下隧道内烟气温度、结构内部温度以及火灾前后衬砌表面回弹值。通过对比火灾前后衬砌结构表面回弹值分析火灾损伤范围,并对综合考虑了结构受火面升温速率、最高温度及其持续时间的温度效应与其高温损伤程度间的相关性进行研究。研究结果表明:火灾下隧道拱顶处温度最高,并沿拱腰、边墙逐渐降低,且温度在结构径向方向传递具有一定滞后性;火源正上方拱顶位置处结构损伤最为严重,回弹值降低率达22.9%;隧道混凝土高温损伤程度随其所受温度效应值的增大而愈加严重。

A field fire test is carried out in a passage-way of a highway tunnel to study the effect of high temperature on the damage degree of tunnel concrete.The measurement contents include the gas temperature,the structure temperature and the rebound value of the structure surface before and after the fire.The fire damage range of lining structure is analyzed by comparing the rebound value before and after fire,and the correlation between the temperature effect and the degree of structural high temperature damage is studied.Further,the temperature effect is related to heating rate,maximum temperature and duration of heated surface.The results show that the temperature at the vault is the highest,and gradually decreases along the hance and abutment wall.And the temperature has a certain hysteresis when the temperature is transferred in the radial direction of the structure.The structural damage at the vault is the most serious where rebound rate decreases by 22.9%.The degree of high temperature damage becomes more serious as the temperature effect value of the lining structure increases.