Abstract: By carrying out similar experiments, the influence of fire source location, wind speed and HRR on smoke control section length was studied under the combined mode of opposite jet and vertical shaft natural smoke exhaust. By changing the position, wind speed and HRR,three groups including 53 senarios were set and the influence of three factors on the length of smoke control section under different working conditions was analyzed and discussed. The results show that increasing the wind speed in the upstream (closer to the fire source) will reduce the smoke control section in the upstream. Increase the wind speed of the downstream (farther from the fire source), and the length of the smoke control section will also be affected by the coupling effect of fire source power, fire source location and other factors. Increasing the power of fire source will increase the thermal buoyancy of flue gas, so that the influence of downstream mechanical wind on flue gas will be weakened.

Key words: road tunnels, opposite jet flow, shaft smoke exhaust, smoke control