Study On Performance-Based Fire Protection Design Applicated In

Urban Traffic Link Tunnel (UTLT) is a novel type underground transportation system. It consists of main tunnel with loop shape and several linked tunnels, and always locates in the important and prosperous district. Compared with common road tunnel, UTLT has more complicated design of structure, ventilation and smoke evacuation systems, greater grade of link tunnels, and more traffic vehicles. Therefore, UTLT bears higher fire risk level, and requires reliable smoke control strategies and people evacuation strategies, to ensure the fire safety of UTLT. The main study object of this paper is the CBD UTLT, which will be built in Beijing, China. And the study emphases is to expore its optimal smoke control strategies and people evacuation strategies.Through investigating the characteristics and the development status quo of UTLT, and analyzing the research methods and results of fire smoke and people evacuation of tunnels, the research method of the performance based fire protection design to research the fire safety of UTLT was put forward.Full-scale tests and numerical simulations were carried out in two underground traffic tunnels with longitudinal ventilation system in Beijing. The simplified methods to build axial fan and jet fan models and to set the boundary conditions of jet fan were obtained. This research results were the important reference for the simulation research of smoke control of CBD UTLT.In this study, the method of the performance based fire protection design was applied. Through carefully analyzing the characteristics of the structure, ventilation and smoke evacuation systems, the fire risk level of this tunnel, 5 typical fire scenarios were built in this tunnel. The numerical simulation software, ANSYS FLUENT6.3.26 was adopted and used to build the full scale tunnel model of CBD UTLT, and investigate the generation, spread and diffusion of the smoke and the reasonable smoke control strategies of 5 designed fire scenarios in this tunnel. The boundary conditions for tunnel fire simulation were set reasonably from the research results of full-scale tunnel ventilation tests.The human evacuation strategies of CBD UTLT under different evacuation scenarios were analyzed, and the corresponding Required Safe Egress Time (RSET) were also calculated. Comparing Available Safe Egress Time (ASET) with RSET, it was found that, in each fire scenario, the restricited persons can evacuate safely under the resonable smoke strategy. This indicated the optimal smoke control strategy and people evacuation strategy of CBD UTLT were established finally.