AbstractBecause of their adverse impact on social infrastructure and economic property, gas explosions are among the most dangerous disasters that can befall utility tunnels. Flame propagation is the most intuitive manifestation during the explosion process. It can be significantly influenced by spatial obstacles. To analyze the propagation law of gas explosions in utility tunnels more realistically, an explosion model of the utility tunnel was established by considering actual spatial obstacles, including the pipeline support and reserved frame. The flame propagation characteristics, including the flame shape, temperature distribution, and propagation velocity, were analyzed systematically. Results demonstrate that spatial obstacles have a prominent influence on flame evolution laws. Flame propagation is disturbed but not completely blocked by spatial obstacles. Rather, irregular flame shapes and wrinkles of the flame front are easily developed. The explosion process is insufficient because of the existence of residual methane in the obstacle area. Flame propagation velocity is improved remarkably, whereas temperature distribution is affected slightly. In particular, the spread velocity increases with the increase of propagation distance. The maximum velocity of monitoring surfaces can be improved by 60% under conditions with obstacles.