Investigation Of Combustion Mechanism And Safety Experiments Of Fire Processes In Long Tunnel With Asphalt Pavement

The dissertation describes a comprehensive investigation of the disaster-prevention safety performance of the asphalt pavement in long highway tunnels by the experiment carried out on the site of Cangling road tunnel with a length of 7.6km of the Tai-Jin expressway.The paper conducted the combustion division range of the asphalt pavement in conflagration process by experiment with the thermo-gravimetric analysis (TGA), the auto-ignition temperatures and the heat-releasing rates of the modified asphalt, flame-retardance asphalt and asphalt mortars. The direct combustion testing in laboratory and valuation method was established for the asphalt pavement in the long highway tunnel. Whether the asphalt pavement can easily burn in conflagration process or not is determined by the direct combustion testing of the SBS modified asphalt, flame-retardance asphalt and mixtures.The scale model tunnel burning test in the laboratory was performed under the condition of various ventilation velocities. An integrated image and data auto-acquisition system of tunnel burning model is thus developed.Based on the chemical dynamics and the thermodynamics, this paper details the burning process mathematically, and constructs a three-dimensional model for the asphalt pavement in highway tunnel simulation to describe the conflagration process, which was verified by the scale model tunnel burning test in laboratory.Furthermore, an analysis was carried out for the distribution rules of temperature field and smog of the Cangling road tunnel under different fire loads and ventilation velocities by the numerical simulation based on the network parallelled technology. It further evaluated the asphalt pavement performance in conflagration process and the influence of asphalt pavement on the temperature and smog. It turns out that long highway tunnels should be paved with the asphalt pavement.Recommendations and suggestions were given for the asphalt pavement structure layers combination of the expressway. An overall evaluation of the disaster-prevention safety performance of the asphalt pavement in long highway tunnels was carried out. Finally, the corresponding countermeasure of disaster prevention and mitigation was proposed in the paper.