Study On Smoke Spread Law In Underground Commercia Street Fire

As a common form of underground construction, Underground Commercial Street to the urban economic development, people’s lives convenient, but also greatly increased fire safety hazards. In this paper, combining theoretical analysis with simulation analysis, fire smoke flow characteristics of the underground business street of in shops and pedestrian passage were studied.First, on the theory basis of the limited construction fire development and smoke spread and control, combing with the functional structural features of underground business street, its fire characteristics and smoke flow characteristics were analyzed. Its characteristics were pointed out, such as more combustible, large fire load, big fire probability and the case of fire, more smoke hazards, more difficult safe evacuation and more casualty loss once on fire. Then fire smoke control measures of underground business street were analyzed comparatively.Secondly, combining with the actual situation of the second fire zoning in Huainan Underground Commercial Street, the fire load, fire growth model, the emission of smoke and other fire parameters were determined. And six different fire scenarios and comparison of programs were designed. Then, fire and smoke simulation model of Underground Commercial Street was established with simulation tool PyroSim and FDS.Finally, comparing the simulation results of fire smoke flow in six different fire scenarios, the variation of smoke temperature, CO concentration, smoke layer height and the visibility in fire shops and pedestrian passage were analyzed under natural filling and mechanical exhaust, and the influence of fire source power, fire source location, smoke emission and air supply on the smoke flowing in the walkways were studied. The analysis results indicate that:temperature, CO concentration decrease, the smoke layer height increase significantly under mechanical exhaust, but no improvement at visibility; underground business street smoke is more inclined to spreading to the channel ends where safe exit has the same opening toward with fire shop; increasing fire power promote smoke spread, fire source location effects smoke spread paths and extent; in a certain extent, increasing smoke emission and air supply reduce the temperature, CO concentration and visibility in walkways, but impact the smoke stream, smoke layer is highly unstable and flue gas turbulence increase.Research process and conclusions have a certain practical significance which provides a reference basis to fire performance optimization design, fire safety evacuation and fire risk assessment of the underground business street.