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以港珠澳大桥工程海底隧道为依托,采用明火试验与数值模拟方法研究了隧道管节结构在火灾下的温度分布及防火技术方案。基于被动隔热技术设计了玻镁防火板单层拼装与双层错缝拼装、保全板单层拼装、防火涂料单层喷涂等3种类型多种试验工况,测试了管节结构构件表面、钢筋保护层等关键位置的温度变化,得到了不同防火方案的隔热效果。基于有限元热传导瞬态分析方法,研究了小汽车、公交车、重型货车、RABT曲线4种典型火灾对管节结构的温度影响,得到了有、无防火板条件下管节结构体内的温度梯度、衰减规律与火灾影响深度,论证了防火隔热对管节结构火灾安全的保护效果。结果表明:防火涂料存在易掉落等现象;玻镁防火板单层拼装方案下,试验构件表面温度超过380℃,不满足耐火极限要求;玻镁防火板双层拼装与保全板单层拼装方案可以满足耐火极限要求,但需做好填缝等构造要求;无论何种隧道火灾升温曲线,管节结构内温度呈现负指数衰减形式;在双层玻镁板隔热条件下,结构受温影响深度为15~20cm,无隔热措施时,结构受温影响深度约为30cm。
Relying on the Harbor Crossing of Hong Kong-Zhuhai-Macao Bridge Project, the open flame test and numerical simulation method were used to study the temperature distribution and fire prevention technology scheme of tunnel pipe joints under fire conditions. Based on the passive thermal insulation technology, three kinds of test conditions including single-layer assembled glass-magnesium fireproof board and double-layer wrong-seam assembled, single-layer assembled insulation board and single-layer fireproof coating were designed and tested. Reinforced protective layer and other key locations of temperature changes, have been different fire safety solutions. Based on the finite element heat conduction transient analysis method, the influence of four typical fires on the joint structure of the car, bus, heavy goods vehicle and RABT curve was studied. The temperature gradient in the joint structure with and without fire protection was obtained , The law of attenuation and the depth of fire effect, demonstrate the protection effect of fire and heat insulation on the fire safety of pipe joint structure. The results show that the fireproof coating has the tendency of falling easily. Under the single-layer assembly of glass-magnesium fireproof board, the surface temperature of the test component exceeds 380 ℃, which does not meet the fire resistance requirements. Can meet the fire resistance requirements, but the construction requirements such as caulking need to be well done. No matter what kind of tunnel fire heating curve, the temperature in the pipe joint structure presents a negative exponential decay form; under the condition of double glass-magnesium board insulation, the structure is affected by temperature Depth of 15 ~ 20cm, no insulation measures, the structure affected by the temperature of about 30cm.