Numerical Meso-simulation Of Open-graded Asphalt Macadam Used To Prevent Reflection Cracks

By tests and finite element analysis for the macro-structure of pavements, researchers found that the open-graded asphalt macadam can prevent the reflection crack in asphalt pavements, but very few people can explain it on meso-level. A random aggregate structure model for the open-graded asphalt macadam was established in this thesis, based on this model, then the meso-mechanism that the open-graded asphalt macadam can prevent reflection crack was analyzed by DEM (Discrete Element Method) to help the researchers understand this problem better.A circular random aggregate structure model in squeezed state was established by DEM, the meso-parameter of the model for DEM was fitted from the elastic modulus and compressive strength of the open-graded asphalt macadam by numerical uniaxial test. The specific method how to establishes loose circular random aggregate structure model was deeply studied in this thesis by throwing particles into the model, particles in the model should not overlap each other, random convex polygon aggregate structure model could be produced by the process of extension to convex polygon based on the circular model, it may be helpful for deep research on asphalt concrete.To establish the relationship between the meso-model and the entire pavement structure, the idea of displacement method was used, a rectangle in the pavement structure model was taken as the meso-model, and it should be ensured to be completely continuous with other parts of the pavement structure model, then the deformation results of the meso-model in the worst loading conditions was calculated by the finite element analysis of the entire pavement structure, it was used to be the load conditions for meso-analysis.DEM which is based on the discrete system can be well used to analyze the open-graded asphalt macadam structure. The discrete element analysis after the assignment of meso-parameters and loads to the model shows that the greater porosity of the open-graded asphalt macadam allows aggregates more space to coordinate to prevent extension of the crack.It is a relatively new method to analyze the asphalt mixture by DEM on meso-level. It is believed to have a great development to help researchers better understand the asphalt mixtures.