Abstract: In the case of power distribution box fire occurred outside shield machine in narrow tunnel during construction, the mesh model including tunnel, fire source, ventilation pipeline and so on was created and the blocking smoke effect of water curtain was simulated. Then some improvements were made based on the defect of original shield machine water curtain system, and the blocking smoke effect of improved water curtain system was verified. As well as the spread of smoke in tunnel was studied by changing numbers and flow rates of sprinklers. The results show that water curtain can effectively prevent the external smoke from spreading into the side of shield machine and ensure the security of staff near the driving surface. Reasonable sprinklers layout can make the water droplets distribution more uniform, which can prevent the spread of smoke better. And a modest increase in the numbers and flow rates of sprinklers of water curtain system can improve the blocking smoke effect.

Key words: narrow tunnel, smoke, shield machine, water curtain, numerical simulation