Research On The Rule Of Fire Spreading In Undergroud Garage And On The Fire Extinguishing Measures

Constructing large underground parking garages can effectively alleviate thedifficulty of parking in urban areas. However, this also brings up issues with firesafety. Compared with above surface parking garages, underground parking garageshave a greater risk of fire, which are also more difficult to extinguish, and they are notconductive to the safe evacuation of people.The primary fire hazard in anunderground parking garage is a parked car. A car fire can be triggered by acombination of two categories of fire hazards. Class A fire hazards refer to solidcombustible materials such as car seats, tires, and interior accessories and class B firehazards refer to flammable liquids such as gasoline or other fuelsubstances.Conventional construction regulations of underground parking garages donot have a clear description of the types of fire hazards. However, the types of firehazards are crucial to determining the type of fire extinguishing system that is mostsuitable for an underground parking garage. This uncertainty is likely to be a safetyhazard.In order to confirm the type of fire in the underground garage, statistic analysisof combustion test for a full-scale car has carried out by the author in the first place,and the curve and peak of heat release rate has been obtained. Secondly, t2fire modelQ at2has been used to confirm fire growth factor of the underground garage. Andthe result shows that it’s the superposition of fire growth factor of both intermediatespeed fire and rapid growth fire (0.18750.011720.19922). Then, a simplifiedgeometric model has been set up according to the layout chart of the actualunderground garage with three different kind of fire scenario: car fire, combustiblesolid matter (seat or decorations) fire and combustible liquid (gasoline and fuel) fire.Critical thermal radiation ignition has been used to analyze the diffusion of fire. Wehave obtained the following results:(1) It needs88seconds for the car on fire to ignite the adjacent cars through thermalradiation.(2) It needs78seconds for the oil level on fire to ignite the adjacent oil level through thermal radiation.(3) It needs431seconds for the seat on fire to ignite the adjacent seat through thermalradiation.(4) We can consider the fire in the underground garage the B-type fire place.After the confirmation of the type of fire in the underground garage, the paperhas analyzed deficiencies of water and the high efficiency of foam concentrate inputting out the fire in the underground garage, meanwhile, it has introduced somekinds of automatic fire extinguishing system which is suitable for fire in theunderground garage: the combination of automatic sprinkler system and foam, totalflooding high-expansion foam system and foam spray suppression system. Afterqualitative analysis of merit and demerit of various systems, multilevel fuzzyevaluation and the transition of qualitative problem to quantitative problem, we haveobtained the ranking of the three kinds of automatic fire extinguishing system: thecombination of automatic sprinkler system and foam＞total flooding high-expansionfoam system＞foam spray suppression system.