Research On The Application Technology Of The Highway Tunnel Warm Mixed Flame Retardant Asphalt Pavement

With the economic development of our country and the increase of highway tunnel construction projects year by year,the traditional mixing method will produce more polluted gas that endanger the environment;and with the increasing of car ownership,the traffic pressure is more and more worse,resulted in highway tunnel fire accidents frequently happened,once a fire is occurring,it will seriously affect the highway tunnel pavement structure.Therefore,it is of great practical significance to carry out the relevant technical research of highway tunnel warm mix flame retardant asphalt pavement.Firstly,the causes of highway tunnel fire are analyzed from three aspects: mechanical failure,vehicle collision and combustible combustion,and the combustion process of fire is summarized.By analyzing the advantages and disadvantages of common highway tunnel pavement structure and the performance of admixtures,excellent pavement structure and admixture materials are obtained.Secondly,through the marshall test,the kentucky flying test and the sherenburg asphalt leak test,the mix proportion design of common SMA mixture is carried out.On this basis,the mix proportion design of flame-retardant SMA mixture and Warm-Mix flame-retardant SMA mixture is carried out.Through the cooling effect test,the rutting test,the trabecular bending test and the freeze-thaw splitting test,the road performance of the mixture is analyzed,and the suitable mix of the warm mixing agent and the flame retardant is determined..Thirdly,the tire-pavement model is constructed by finite element method,and the displacement,compressive stress-strain and shear stress-strain indexes of road tunnel pavement structure are simulated.The stress-strain relationship between tire and pavement is established.Then,the distribution law of pavement temperature field under different fire scale and the quantity of asphalt mixture needed for repairing after disaster are obtained by simulation fire test.The flame-retardant effect is verified by oxygen index test,and then the combustion test is carried out to construct the quality loss of asphalt mixture.The relationship model among loss rate,residual road performance and burning time was established.Finally,through the inspection of construction technology analysis,the construction technology of warm mix flame retardant asphalt pavement for highway tunnel is put forward,get the relationship between maximum temperature and fire scale,and the energy saving and emission reduction and social benefits in construction,construction and operation stages are analyzed by life cycle analysis method.It is concluded that the cost of using warm mix flame retardant asphalt pavement is about 1.7%,and the economic and social benefits are remarkable.The application of the results can save resources,protect the environment and reduce fire losses in highway tunnels.In addition,it can improve the road performance of asphalt pavement in highway tunnels,reflecting the design concept of saving environmental protection and safety.