| Low temperature cracking of asphalt mixture is one of the main diseases in asphalt pavement.Under the trend of mechanical-experience design in pavement design,present consideration of cold cracking is mainly based on experience.The classic continuous mechanics theory confronts singularity in the crack tip,and Discrete Element Method is limited by computational efficiency,both of which cannot provide suitable mechanical model for cracking.Peridynamics theory has theoretical advantages in dealing with fracture problems,and is expected to provide a suitable mechanical model for the cracking of asphalt mixture.This article selected the semi-circular bending test as simulation object,built up asphalt mixture numerical model based on bond-peridynamics,analyzed the change of stress and energy in semi-circular specimen during the process of test,and considered the influence of the coarse aggregate,voids and micro cracks on the low temperature cracking of asphalt mixture.The research mainly studies the following three aspects:(1)Semi-circular bending test was used to analyze the low temperature crack resistance of asphalt mixture prepared by different asphalt with different aging extent.The results show that the cracking of asphalt mixture,influenced by a variety of factors,is very complicated.And it is feasible to choose the macro performance parameters of asphalt mixture as the numerical simulation analysis parameter.(2)Numerical model was established based on bond-peridynamics considering the two-dimensional mesoscopic structure of asphalt mixture and was used to simulate the semi-circular bending test.The results shows that the trendendy of loading force with the displacement at loading direction and the cracks expanding rule are both consistent with experimental results,with difference of fracture energy being lower than 6%and the computational efficiency being relatively high,verifying that advantages of peridynamics theory on asphalt mixture crack simulation.(3)The numerical model was used to analyze the deformation and energy distribution in the test specimen.The results reveal that the arching effect caused bimodal trendency of the loading force and the total input energy is partly used in plastic deformation.The fracture energy calculated following AASHTO TP 105-13 are close to the actual energy used for cracking.(4)The 2-d mesoscopic peridynamics numerical model was used to simulate and analyze the influence of void ratio,aggregate size and micro crack on asphalt cracking,the results show that void has dual function on the cracking in asphalt mixture at low temperature and there is a optimal range of void ratio,the resistance of asphalt mixture to cracking is stronger when the aggregate is thicker,and microcrack under small angle with crack direction has great influence on the crack development path. |
