Research On Flue Gas Control Of Quasi-Rectangular Subway Tunnel

With the global economic structure becoming more and more perfect,the infrastructure of every city can meet people's daily needs in an all-round way.Subway is considered as one of the main ways to solve urban traffic problems because of its convenience and large capacity of passengers.However,the problem of subway fire safety has become increasingly prominent.Due to the characteristics of subway tunnel,smoke cannot be discharged in time in case of fire,which will pose a huge threat to people's lives and property safety.Therefore,designing reasonable and effective smoke control scheme in controlling tunnel smoke is an important protective measure for safe evacuation of personnel and property protection.As a new type of tunnel section,quasi-rectangular tunnel structure section reduces the intensive use of underground space and effectively solves the problem of urban core area rail transit construction.However,there is no space for two-way opening of fire doors in this cross-passageway.In this paper,three methods of theoretical analysis,FDS numerical simulation and scale model experiment are used to study the smoke control model of quasi-rectangular subway tunnel with one cross-passageway under the condition that there is no space to install a fire door.Based on the experimental data,this paper summarizes the smoke flow law under the cooperative smoke control mode of longitudinal ventilation of ignition tunnel and positive pressure ventilation of non-ignition tunnel in case of fire in subway tunnel,and analyses the feasibility of using airflow smoke control technology to prevent smoke from spreading to non-ignition tunnel,so as to obtain a reasonable smoke control method and ventilation control parameters for the quasi-rectangular subway tunnel.The main research contents are as follows:Based on the basic theory of subway tunnel fire,the main structural forms of subway tunnel and smoke control methods,this paper analyzes the smoke flow law and smoke control mode of quasi-rectangular subway tunnel with a cross-passageway under fire conditions.According to the similar theory of Froude,an experimental platform for scale model of 1:3 quasi-rectangular subway tunnel is established.The smoke flow law and its control effect of fire is studied under the coordinated ventilation mode for the two fire source locations in a quasi-rectangular subway tunnel when there was no fire door in a cross-passageway.At the same time,based on the experimental platform of scale tunnel model,a geometric physical model is established by using FDS numerical simulation software to simulate the effect of cooperative air supply mode on smoke flow law in the quasi-rectangular tunnel when there was no fire door in a cross-passageway.The reasonable smoke control method and ventilation control parameters of the quasi-rectangula tunnel are obtained,which provides a scientific guidance for the actual model experiment.Numerical simulation and experimental results show that when the longitudinal ventilation wind speed of ignition tunnel is not less than 2.9m/s after a fire occurs in a quasi-rectangular subway tunnel,the smoke can be effectively controlled without regurgitation.When the positive pressure air velocity at both ends of non-ignition tunnel is not less than 1.6m/s,it can effectively prevent smoke from entering non-ignition tunnel through the cross-passageway.