Research On Fatigue Damage Of Asphalt Mixture Under Different Loading Frequencies

For its excellent service performance, asphalt pavement was built more and more in the construction of expressway. It is one of the main destruction forms on the asphalt pavement. It is very important to research the fatigue performance under a specific traffic and environment conditions which has been subject to road workers attention. The road surface materials are subject to complex and ever-changing load, environmental conditions, as well as the complexity of the material constitutive relations, only evaluate the performance under the particular conditions is not the overall performance of the material. The research of asphalt mixture fatigue performance in different age and different temperature was more systematic. As very few studies of asphalt mixture fatigue performance under different loading frequencies are carried out. Therefore, in order to better understand the fatigue performance of the asphalt mixture under different conditions, it is necessary to carry out the reserch on fatigue damage of asphalt mixture under different loading frequencies. And it will play a positive role in prolonging the service life of asphalt pavement.Through the indoor fatigue test, it obtained the change trend of parameters k and n of the fatigue equation, and also can obtain fatigue equation relations under different loading frequencies ,which were used the fiting result of stress level and fatigue life. By the relation theory of the damage mechanics and the attenuation regularity of asphalt mixture stiffness modulus, the fatigue damage model was established based on the attenuation regularity of stiffness modulus for the asphalt mixture, which provides the basis of studying fatigue damage characteristics under different loading frequencies. It is also discussed the existence of fatigue limit of asphalt mixtures by the changing regularity of the fatigue damage.Through the conclusion of test, the theory of fatigue dynamic strength was verified. And the S-N fatigue equation was established based on the actual stress level. Analysis showed that equations based on actual stress level under different loading frequencies can be unified in the same fatigue curve, which provides the convenience of analysing the asphalt mixture regularity of fatigue under different loading frequencies.Finally, based on the former result, the deficiency of this paper is analyzed. It gives some advice on how to carry on the subsequently research.