Long Highway Tunnel-site Fire Test And Lining Structure Fire Resistance

With the rapid development of the construction of road traffic, more and more Extra-long highway tunnels are increasing, meanwhile the probability of tunnel fire is also increasing. It is a serious threat to the safety of human life and property and even lead to collapse of the tunnel structure once the fire occures in a long tunnel. Therefore, the study of field fire test and structure fire resistance of Extra-long tunnel brings very important significance. This research aims to explore the Yanmenjie tunnel fire on Changde-Jishou highway. A full-scale field fire test together with computer numerical simulation is adopted in this study. The main contents and findings of this research are as follows:(1)A integrated field test system of tunnel fire is established and some related parameters are obtained about environmental temperature, heat release rate, surrounding air speed on the basis of field investigation in Yanmenjie Tunnel on Changde-Jishou highway.(2) Through the field tests to the tunnel fire conditions under different heat release rates and wind velocity, the vertical temperature distribution law of the center of different sections, longitudinal temperature distribution law of the tunnel vault, the law of hot smoke settlement and law of smoke spread inside the tunnel under different conditions are obtained. Besides, the reliability of ventilation exhaust system of the tunnel is also verified.(3)Conditions of field fire test are simulated by using FDS. The numerical simulation results correspond principally with the experimental results through contrast and analysis, which shows that the results of the numerical simulation are reliable.(4)Through the numerical simulation to high-power fire whose heat release rates up to 30MW and 50MW, the temperature distribution law, the maximum temperature of the tunnel vault and the high temperature distribution inside the tunnel under different conditions are obtained. The findings can provide some technological basis for the tunnel structure protection and damage assessment and reinforcement after the disaster. (5)A force calculation model of tunnel lining structure is established in this study, which aims to evaluate the security of tunnel lining structure in fire. The results shows that the tunnel lining structure will be destroyed when the temperature is above 1000℃or the temperature reaches 800℃with burning time over 2 hours.Currently, merely a small amount of research has connection with the full-scale field tunnel fire tests in our country, the test data and research findings of tunnel fire are extremely valuable. Therefore, the test data and research findings in this research will provide valuable reference for the further research on tunnel fire and fire resistance of the tunnel structure.