为了消除或降低综合管廊燃气舱内管道在施工过程中产生的有害烟尘,保证作业环境有害烟尘浓度符合国家焊接烟尘极限允许浓度要求,为燃气舱内管道焊接作业提供有效可行的通风控制措施至关重要。结合氩电联焊在城市地下综合管廊燃气舱内施工过程的实际应用,采用FLUENT软件分别对自然通风工况和机械通风工况进行焊接烟尘扩散模拟,分析不同换气次数对作业人员职业健康的影响。通过分析模拟结果可知,当燃气舱内强制通风换气次数2次/h时,为项目最优烟尘稀释方案；仅利用管廊设计风口进行自然通风,根本无法达到国家焊接烟尘极限允许浓度要求;如果采取强制通风换气,应充分考虑作业人员职业健康安全与施工能耗的双重影响,进而确定最优烟尘稀释方案。对燃气管廊安全施工具有指导意义。

In order to eliminate or reduce harmful smokes and dusts generated when constructing pipelines inside gas tank of integrated pipe racks and ensure that the concentration of smoke and dust conforms to the maximum allowable concentration of welding fumes stipulated by the state,it is of great significance to provide effective and feasible ventilation for pipelines welding operation within gas tank.According to the application of GTAW+SMAW in the gas tanks of urban underground integrated pipe racks,the diffusion of welding smokes and dusts in natural and mechanical ventilation are simulated separately by applying FLUENT,and the influence of different ventilation ratio on occupational health of operating staff is analyzed.By a series of analyses and simulations, it turned out that the optimal solution for fume-dilution can be achieved when the forced ventilation ratio within gas tank is 2 times/h in this project.The study shows that it is impossible to meet the maximum allowable concentration for welding fumesjust with the design air inlet at integrated pipe racks for natural ventilation.Supposing that forced ventilation is adopted, the occupational health and safety of staffs and energy consumption should be also fully taken into account to determine the optimal solution for fume-dilution.