| With the accelerating of urbanization,the urban traffic problems are getting worse,which can not satisfy people’s traveling needs.Subterranean space resources start to be exploited,and the Urban Traffic Link Tunnel(UTLT)appears.There is a high probability of fire in the UTLT which has a special structure,plenty of curved tunnels and traffics.In case of the tunnel fire,the smoke is prone to backflow,increasing smoke control difficulties,which seriously threat to the lives of people.Researches on smoke movement rules and optimize smoke exhaust measures of “日” UTLT are carried out in this paper.Take advantage of Pyrosim software to build the tunnel model.According to the relevant information,three fire conditions are set.Fire is located at the major tunnel,link tunnel and branch tunnel.No ventilation,semi-transverse ventilation and transverse ventilation are set in the major tunnel and link tunnel.There are three ventilation methods for horizontal ventilation,and two ventilation methods for non-ventilation,and longitudinal ventilation are set in branch tunnels.Researches on the different fire scenarios distribution of fire parameters are carried out,and smoke control indicators are contrasted.Above all,it is verified that the smoke control plan is reasonable and practical,the findings are as follows:(1)Without ventilation,the fires in the major tunnel and the branch tunnel are not satisfied with the smoke control index.When the fire is in the link tunnel,it is not satisfied with the smoke control index.The smoke spreading range is the largest,and the major tunnel is almost full of smoke.Compared with the major tunnel and the branch tunnel,the fire situation is more dangerous.(2)Under the condition of semi-transverse ventilation,with the fire in the major tunnel,the right branch tunnel of fire is full of smoke,affecting the safe evacuation.When the fire is in the link tunnel,the smoke is controlled in the link tunnel.When the fire is in the branch tunnel after turning on the jet fan because of the endwise air-flow,the flue gas rapidly exhaust,the jet fan is set at the junction of the branch tunnel and the major tunnel,which can effectively prevent the smoke from spreading to the major tunnel.(3)Under the condition of transverse ventilation,when the fire is in the major tunnel,satisfying the smoke control index,for tunnels with more connecting passages,full transverse ventilation has better smoke control effect than semi-transverse ventilation.When the fire is in the link tunnel,it satisfied the smoke control index.For the straight connected tunnel,the difference of smoke control effect between the semi-transverse ventilation and the transverse ventilation is small.(4)When the fire is in the major tunnel,with regards to the problems and disadvantages,majoring smoke control plan is put forward.After the contrast and the analysis,the majoring smoke control plan has good smoke control effect,the smoke can be controlled in a certain range.The results show that the combined smoke exhaust mode of air supply semi-transverse ventilation and jet fan can meet the smoke control requirements of underground ring tunnel with more connecting passages. |
