Research On Security Early Warning Model Of Urban Rail Transit Operation Phase Based On BIM

The process of urban modernization development in China has grown rapidly.Urban rail transit has become the main means of transportation for some first-tier cities,effectively alleviating traffic congestion.In the event of an accident in urban rail transit,it often causes harm to passengers,the public,and employees,and has a great negative social impact.Fire accidents have the highest proportion and the greatest impact in urban rail transit safety accidents,so the safety of urban rail transit fire safety is particularly important.Traditional urban rail transit fire simulation has many problems in modeling,such as lack of necessary material information,inaccurate environmental model,and cumbersome modeling process.The BIM-based subway station simulation model can provide a fire scene that matches the actual situation and improve the accuracy of the simulation.This paper firstly uses literature research,field research,model analysis,theory and practice to propose an implementation plan for applying BIM technology to urban rail transit emergency management.BIM technology is used to establish a three-dimensional model of the subway station,and perform numerical simulation of fire in a metro station in Harbin.It is docked with the Pyrosim fire simulation software in DXF format to study the ventilation mode at different fire source locations,different fire source powers,and the screen opening method to the temperature field and velocity field of the station when the subway fire occurs.As well as the influence of visibility and CO concentration distribution,it can be concluded that the tunnel auxiliary fan and the main fan of the platform can be simultaneously turned on to reduce the station temperature and toxic gas concentration more effectively,and increase the visibility of the platform.Compared with the main fan exhaust mode,the platform temperature is reduced by 18.1% and the carbon monoxide volume fraction is reduced by 25%.Compared with the natural smoke exhaust mode,the platform temperature is reduced by 46.2%,and the carbon monoxide volume fraction is reduced by 42%.Although the full opening of the screen door can reduce the temperature of the platform temperature field and the concentration of toxic gas,it will cause the disorder of the airflow organization of the platform,and the excessive wind speed of the evacuation channel is not conducive to personnel evacuation.Selecting the one-side opening scheme of the screen door can meet the requirements of lowering the temperature of the platform and satisfying the distribution requirements of CO concentration and visibility,which is the most suitable choice.Then the BIM model of the subway station was imported into the Pathfinder safety evacuation simulation software in DXF format.Through the on-site investigation and related specifications,the behavior characteristics of the evacuated personnel and the passenger flow at the peak hour of the station were determined.The evacuation simulation parameters were set and the peak of the subway was analyzed.The hourly no-train,single-train and double-train evacuation at the same time,it is concluded that the evacuation capacity of the subway can meet the requirements without trains and single trains,and the evacuation time is longer when the two trains are at the same time,and the fourth entrance and exit is utilized.The rate is low.Finally,according to the smoke spread law and the simulation results of personnel safety evacuation simulation,the emergency plan under the subway station platform fire was compiled,and some optimization measures were proposed to strengthen the fire safety of the subway station against the existing safety hazards..