港珠澳大桥沉管隧道接头耐火性能试验研究

为研究港珠澳大桥沉管隧道管节接头的耐火性能,在1∶5缩尺寸模型内进行了4次单孔接头整体在不同特性防火板保护下的火灾试验。试验主要量测了火灾全过程中防火板背火面、混凝土、钢筋、防火隔断、止水带等位置温度随时间的变化情况。结果表明:1)1 200℃火灾持续2 h,接头在25 mm～30 mm厚单层防火板保护下,混凝土外表面温度不超过380℃、止水带温度不超过70℃;2)防火板背火面温度场主要受炉内温度分布的影响;3)火灾下防火板受火面裂纹的产生与板材支承条件相关,裂纹的形态与板材性质相关;4)考虑板材厚度影响,港珠澳大桥沉管隧道所使用的防火板综合耐火性能最优。

Experimental study on fire resistance of joint of Sunken Tube Tunnelof Hong Kong-Zhuhai-Macao Bridge

To study the performance of tube joints in the sunken tunnel of Hong Kong-Zhuhai-Macao Bridge, four fire tests were carried out for the whole single-hole joint under the protection of fireproof boards with different characteristics in the 1:5 scale model. The temperature changes with time of the back surface of fireproof board, concrete, steel bar, fire partition and water stop were measured in the experiment during the fire. The experimental results show that: 1) Under the condition of high temperature for two hours at 1 200 degrees Celsius, the outer surface temperature of concrete did not exceed 380 degrees Celsius, and the temperature of joint water stop protected by single layer fireproof board of 25 mm~30 mm thick did not exceed 70 degrees Celsius; 2) The back surface temperature field of fireproof board was mainly affected by the temperature distribution in the furnace; 3) The occurrence of cracks on the fire face of fireproof board under fire was related to the supporting conditions of the plate, and the morphology of cracks was related to the property of the plate; 4) Considering the influence of plate thickness, the fireproof board used in the sunken tube tunnel of Hong Kong-Zhuhai-Macao Bridge has the best comprehensive fire-proof performance.