基于红外热成像技术烃类火灾下沉管隧道开裂分析*

为了研究烃类火灾下沉管隧道的开裂深度，建造沉管隧道缩尺模型，采用HCinc升温曲线在沉管隧道左、右两侧孔内同时开展明火试验。在沉管隧道火灾试验过程中，利用热电偶和红外热像仪测量沉管隧道的温度场变化，利用红外热像仪对混凝土裂缝位置的温度变化进行监测。基于混凝土内水分迁移原理，结合混凝土裂缝中水和水蒸气的温度变化及混凝土内温度场分布，推断出在点火95 min时，混凝土裂缝开展深度超过150 mm。研究结果表明:在沉管隧道内部发生火灾的情况下，受火侧受热膨胀容易导致沉管隧道外侧混凝土受拉开裂，在沉管隧道抗火设计中，建议考虑内外侧温差导致的混凝土开裂问题。

Cracking analysis of immersed tunnel under hydrocarbon fire based on infrared thermal imaging technology

In order to study the cracking depth of immersed tunnel under the hydrocarbon fire,a scale model of immersed tunnel was built,and the naked fire test was carried out in the traffic tubes on both sides of the immersed tunnel by using the HCinc temperature-rising curve.During the fire test of immersed tunnel,the temperature field change of the immersed tunnel was measured by the thermocouples and an infrared thermal imager,and the temperature change of concrete cracks in the immersed tunnel was monitored by the infrared thermal imager.Based on the principle of water migration in concrete,combined with the temperature change of water and vapor in concrete cracks and the temperature field in the concrete,it was inferred that the development depth of concrete crack exceeded 150 mm at 95 min of the fire test.The results showed that in case of fire inside the immersed tunnel,the thermal expansion of the inner concrete exposed to fire was easy to lead to the tensile cracking of the outer concrete.In the fire resistance design of the immersed tunnel,the concrete cracking caused by the temperature difference between the inner and outer concrete should be considered.