Study On Human Evacuation Under Fire In Double-hole One-way Highway Tunnel

With the economy developing and modernization process speeding up,construction of highway tunnel steadily pushes forward.The number of highway tunnel has increased every year and more than half of them are long tunnels.As every coin has two sides,tunnel provides convenience for travel and traffic on one side.On another side,it brings risks of accident,especially fire.The current situation puts forward a higher requirement on operation management and evacuation in tunnel.Therefore,this paper uses FDS and Pyrosim FDS+Evac to establish fire evacuation scenarios based on a tunnel engineer,simulating and analyzing smoke spreading law and evacuation situations to calculate ASET and RSET in different operating modes,then judging whether people can escape safely.In order to adapt to current situation,optimization schemes of fire control facilities have put forwards in this paper.The main contents and achievements are as below:1.Do analysis and summary on tunnel fire causes and characteristics.Basic theory of fire and evacuation principles and guidelines are expounded.2.Establish 4 fire scenarios in different ventilation condition and traffic condition: upstream blockage with ventilation failure,upstream blockage with normal ventilation,upstream unblocked with ventilation failure,and upstream unblocked with normal ventilation.Combined with smoke spread law and personnel safety evacuation criteria,When the upstream blockage with ventilation failure,RSET(476.9s)>ASET(470.4s).This senario can not ensure the safety of personnel;when the upstream blockage with normal ventilation,the personnel evacuated upstream can escape safely due to the critical wind speed;when the upstream unblocked with ventilation failure,RSET(358.9s)<ASET(470.4s).This senario can ensure the safety of personnel;when the upstream unblocked with normal ventilation,the personnel can safely evacuate due to the dilution effect of longitudinal ventilation.Futhermore,it is concluded that safety evacuation not only related to human characteristics but also affected by traffic condition,ventilation condition and evacuation direction.3.In order to shorten ASET and RSET,the optimization schemes for space between two pedestrian cross isles,smoke extraction mode and detection alarm system have been proposed.Different evacuation scenarios with different spaces(200m,210 m,220m,230 m,240m and 250m)were simulated and analyzed.When the space is 220 m,RSET(444.9s)<ASET(482.9s).This scheme can not only ensure the safety of personnel,but also save the cost,which is the optimal setting scheme.It is suggested that existing ventilation be replaced by centralized smoke extraction after comparing and analyzing.Feasibility has been expounded as well.On this basis,effects of different sizes of vent(2m×1.5m,2m×2m,2m×3m)and different opening groups(4,6,8)in centralized smoke extraction mode have been simulated.When 4 sets of exhaust vents with size of 2m×2m were opened,the time when visibility drops to the dangerous value at 50 m,100m and 150 m from the fire source is 436.2s,560.8s and 597.0s.This scheme respectively provide more time for evacuation when compared with others.It is determined that opening 4 groups,2m×2m vents is the optimal scheme for extracting.In addition,it is suggested to replace current detection alarm system with a new one which combines optical fiber grating sensor alarm system with spot infrared flame detection alarm system or image photosensitive detection alarm system according to relevant design guidelines in comparision with common detection alarm systems.