Research On Meso-mechanical Behavior Of Asphalt Pavement Based On Temperature-Load

With the development of transportation,the problem of asphalt pavement damage has attracted widespread attention.Research on the damage of asphalt pavement often uses traditional methods such as finite element method and indoor test.The finite element theory simplifies the pavement structure into a continuous uniform medium,and analyzes the mechanical response of the pavement from a macro perspective,which is mainly reflected in the pavement bearing capacity,the internal stress changes of the structure and the road surface displacement.When the asphalt pavement is damaged,the initiation and expansion of cracks in the structure cannot be explored from a macro perspective.Therefore,the conclusions obtained from the study are limited to the macro level and cannot explain the respective mechanical responses of the asphalt mixture mortar and aggregate.Compared with the finite element method,the discrete element method can reflect the characteristics of the non-homogeneous and discontinuous material of the asphalt mixture,and it can reveal the Microscopic mechanical behavior of its internal structure.Therefore,it is necessary to use the discrete element method to study the mechanical behavior of asphalt pavement.In this paper,the asphalt mixture is simplified to consist of two materials,coarse aggregate and mortar.A discrete element asphalt pavement model is established based on the real asphalt pavement structure and the gradation of each structure.By fitting the uniaxial compressive stress-strain curve of each layer of material,the microscopic parameters of the model are obtained to ensure the correctness of the discrete element model.Based on this,the mechanical behavior of asphalt pavement under static load,rolling load,temperature,etc.is explored,and the mechanical characteristics of asphalt pavement are comprehensively analyzed from macro and microscopic levels.First,the macro-mechanical response of the asphalt pavement under static load is studied,and the calculation of the discrete-element pavement model is verified by comparison with the calculation results of the finite element method.Secondly,because the pavement model is small,loading through a real tire model is more complicated.This paper uses a method of applying a force to the tire to reach the road surface ground pressure to investigate the mechanical response of the asphalt pavement under different loads.Subsequently,the initial temperature of the model was given,and the change of the internal mechanical behavior of the asphalt pavement structure under the combined effect of temperature and load was further investigated by loading the pavement model after the temperature change.Finally,this paper carried out a three-point bending test and simulation on the surface layer material,and analyzed the mechanical behavior of the asphalt mixture under different temperature conditions such as stress changes,particle displacements,crack initiation and propagation.The research results show that this paper uses the fitting method to obtain the mesoscopic parameters to establish a correct discrete element model.The particle translational speed,rotational speed,and rotation angle of each structural layer of the pavement are positively related to the load force and temperature increase,and negatively related to the pavement depth.Temperature affects the fracture deflection of the asphalt mixture.As the temperature increases,both the particle displacement and the azimuth angle increase.In addition,temperature has a certain effect on the fracture position of the asphalt mixture.