基于CFD的箱梁桥内部火灾模拟及逃生分析

CFD Based Analysis on Research of Fire Hazard inside Box Girder and Safety Evacuation

针对某些有特殊通行需求的公路箱梁桥内部可能遇到的火灾情况,基于CFD对比分析了混凝土箱梁腹板开设通风孔和人行孔前后火灾温度场和烟气状态的差异,以及其对于人员逃生的影响。首先建立了箱梁及车辆燃烧模型,确定热释放速率及风场环境,进而模拟了箱梁内部不同热释放速率下的车辆火灾模型;从温度、热流量、烟气等特征进行比对分析,并参考隧道逃生研究成果给出了公路箱梁桥火灾时人员逃生衡量准则,分析结果表明,腹板孔洞对于降低火灾灾害以及人员逃生具有重要作用,相关结论可为类似桥梁抗火设计提供参考。

Considering the possibility of internal fires of box girder for bridges under special conditions,the differences of temperature and smoke fields are compared by using CFD(Computational Fluid Dynamics) in two circumstances,namely with ventilation and man holes and without holes.First,models of bridge and types of vehicles are established;Next,the burning HRR(Heat Release Rate)and wind field are determined.Then the vehicles fires are simulated inside the box girder and features such as flame temperature,heat flow,and smoke conditions are analyzed and compared.Finally,the safety of evacuation is assessed.The results show that the ventilation and man holes of box girders are of great significance to reduce fire hazards and personnel evacuation,and the research may provide references to related bridge fire-resistant design.