Study On Fire Safety Numerical Simulation Of Complex Underground Space

With the development of national economy and the rapid growth of urban population,the development and utilization of urban underground space has gradually become an indispensable part of urban sustainable development,which is an important measure to improve urban transportation,functional pattern and living environment.However,due to the fact that most of the underground buildings are underground,the space is relatively narrow and closed,and the people are relatively dense,once a fire occurs,the fire spreads rapidly,and the smoke spreads and gathers,which will cause huge casualties and economic losses.Therefore,to control the fire in time and master the flow law of smoke in the fire field,so that people can evacuate safely and reduce casualties,has become an important content of underground building fire research.Using the numerical simulation software to simulate the smoke spread process of underground building fire can grasp the smoke flow law of underground building,which has guiding significance for verifying the effectiveness of fire fighting measures in underground building fire.In this paper,through the combination of BIM(building information modeling)model and FDS,the direct conversion from BIM model to FDS model is realized.The problems of rough,low accuracy and serious loss of details in the traditional FDS modeling process are overcome,the accuracy of fire simulation results is improved,and the foundation for the accurate simulation of underground space is laid.On this basis,this paper selects three representative complex underground space structures,i.e.comprehensive pipe gallery,subway station and underground garage,and introduces the BIM model into the fire simulation software FDS to establish a refined semantic fire numerical model for the case analysis of underground buildings,and carry out the fire numerical simulation research.Under the condition of adding mechanical smoke exhaust and spraying,the smoke spread rate,temperature,CO concentration and visibility in the fire site are improved in the scene with mechanical smoke exhaust.Moreover,different smoke exhaust systems have great influence on the smoke spread in underground buildings.Properly adjusting the position of smoke exhaust port can greatly delay the smoke spread in the fire site and delay the smoke spread The time of injury to personnel,extend the safe evacuation time available for personnel.This study can provide some reference conditions for fire protection design,and provide reference for fire protection project evaluation and fire investigation.