Study On Fire Smoke Control And Personnel Evacuation In Urban Underground Garage Connecting Tunnel

In view of the serious ground traffic congestion and underutilization of parking resources in big cities,especially the core areas of cities,many cities in China have begun planning or building urban underground roads.Among them,the urban underground garage connecting tunnel is a new type of urban underground traffic connecting tunnel（Urban Traffic Link Tunnel,referred to as UTLT）,which has many branch tunnels,complex structure,narrow section,large traffic volume,low vehicle speed,high fire risk,etc.Features.Therefore,it is necessary to formulate effective fire smoke control and personnel safe evacuation plans to ensure the efficiency of UTLT’s fire smoke exhaust and personnel safe escape.In this paper,the connection tunnel of the eighteen ladder underground garage in Chongqing is the research object,and the method of combining theoretical analysis,model test and numerical simulation is used to study and analyze the fire smoke control of this type of tunnel and the corresponding safety evacuation of personnel.The main research work and research results are as follows:1)Through the basic theoretical analysis of numerical simulation,numerical simulation of 1:3 scale tunnel and model test,the comparative analysis of the fire smoke movement,visibility and temperature distribution law verifies the rationality of the fire smoke control numerical simulation model in this paper.2)Based on the detailed analysis of the design standards of the tunnel fire scene,combined with the numerical simulation model design of the 1:3 scaled tunnel and the structural characteristics of the engineering tunnel,this paper selects two parts:the straight section of the local loop tunnel,the straight section of the loop tunnel and the ramp intersection.For typical fire locations,20 fire smoke exhaust conditions have been established;at the same time,the determination index of fire smoke control related to the tunnel and the division method of tunnel smoke prevention zone were determined.3)FDS（Fire Dynamics Simulator）numerical software is used to simulate the fire smoke flow characteristics of the straight section of the ring tunnel under 12 kinds of fire smoke exhaust conditions such as no longitudinal wind speed,longitudinal wind speed+natural smoke exhaust,longitudinal wind speed+mechanical smoke exhaust,etc.Analysis;The simulation analysis of fire smoke characteristics under 8 different longitudinal wind speeds was carried out on the straight section of the ring tunnel and the intersection section of the ramp.The research puts forward the recommended schemes of fire smoke control for the straight section of the loop tunnel,the straight section of the loop tunnel and the intersection of the ramp.4)In response to the above recommended fire smoke control schemes,using Pathfinder evacuation software,a simulation analysis of the safety evacuation of people with 20 and 26 different evacuation opening layout schemes was carried out on the straight section of the ring tunnel,the straight section of the ring tunnel and the ramp intersection respectively.It mainly studies the evacuation process,the necessary safe evacuation time T_REST and the available evacuation time T_ASET at key locations,and compares and analyzes whether it meets the criteria of T_REST<T_ASET personnel evacuation judgment.Finally,the recommended layout schemes for the safe evacuation of people on the straight section of the ring tunnel,the straight section of the ring tunnel and the intersection of the ramp are proposed.The research results of this paper can provide guidance for the fire smoke exhaust,personnel escape,and operation management of the urban underground garage connection tunnel.At the same time,it has promoted the development of urban underground roads.