The Research On The Combustive Mechanisms Of Asphalt Pavement In Tunnels And The Factors Affect Them

Based on its own special structure,the tunnel is the place where fire accidents might occur once the collision happens inside of it.And when fire accidents happened in the tunnel,the static temperature will increase rapidly.Fire accidents may generate a great number of smoke and cause severe damages.Therefore,it is necessary to study on the mechanisms of combustion of asphalt pavement and their influences.After summarizing the research on the combustive experiments of asphalt mixtures,the application of flame retardant and theoretical analyzing around the world.This dissertation started from the research of the seepage and flame mode of combustive liquids on the asphalt mixtures,and analyzed the combustive mechanisms of asphalt mixtures.To specify,water,alcohol and gasoline were selected and analyzed during the experiments of seepage and flame modes.Then the combustive mechanisms of asphalt mixtures and their influences were studied during experiments.Last but not least,the distribution of static temperature and flow of smoke were stimulated by using Computing Fluid Dynamics software.The results are as follows:(1)SK-70 basic asphalt,SBS addiction and Ammonium Polyphosphate flame retardants were selected and by finishing experiments of penetration,softening point and ductility and the additive doses of SBS modifiers and Ammonium Polyphosphate flame retardants were determined.In addition,the Optimized Asphalt Compounds(OAC)would be decided under the experiments of marshall stability and dynamic stability.(2)the research of the seepage and combustive modes were studied.By pouring the same volume of liquid into asphalt mixtures,the seepage mode of liquids was carried out.The result shows that the percentage of vertical seepage of AC-13 mixtures was higher than the number in SMA-13.When it comes to combustive modes,the percentage of vertical flame was much higher than the percentage of horizon direction.(3)the combustion mechanism of asphalt mixtures were furtherly studied in this dissertation.By lighting up the gasoline itself and pouring it to the asphalt mixtures,the result indicates that the flaming time of asphalt mixtures was twice as much as the time of flaming gasoline itself.Therefore,asphalt has had a positive impact on the combustion of asphalt mixtures.In addition,the aggregation and performance of asphalt were selected as two factors that can affect the combustion mechanism of asphalt mixtures,it turned out that the flaming time of SMA-13 asphalt mixtures was longer than AC-13's.While on the side of performance of asphalt,the temperature of mixtures which were added flame retardant was lower than those did not.(4)The numeral simulation tests were also conducted by using Computing Fluid Dynamics software.The results show that the flow of fire was vertical with the driveway at the very beginning,and shifted to the direction which was parallel with driveway.In addition,when ventilation was taken into consideration,the flow of smoke will be affected by it.And based on the result of simulation,the rescue plans and safety suggestions can be made.