Numerical Simulation Of Low Temperature Crack Resistance Of Asphalt Mixture

In order to study the influence of aggregate characteristics of asphalt mixture and material defects(voids)on the fracture performance of asphalt mixture under low temperature environment,the fracture performance of asphalt mixture is enhanced under the condition of cost control,and the road performance of asphalt mixture in seasonal frozen area is extended.Based on Monte Carlo algorithm,aggregate is randomly put in and a two-dimensional(2D)finite element model of asphalt mixture is established.A virtual fracture model of heterogeneous materials is designed by establishing a finite element model.The effect of the fine structure of the material on the fracture properties of the material was studied.The appearance and shape of asphalt mixture matrix and its initial defects are explored The influence of micromechanical phenomena on macro mechanical properties of asphalt concrete in seasonal frozen zone under low temperature is studied.When studying the influence of aggregate characteristics on the anti cracking performance of asphalt mixture,asphalt mixture is regarded as three-phase composite material composed of coarse aggregate,asphalt mortar and asphalt mortar aggregate interface.In this paper,the random aggregate distribution digital specimen is generated by MATLAB self programming program,and the aggregate characteristics(aggregate content,aggregate roundness,aggregate gradation,aggregate particle size)are analyzed by using ABAQUS finite element software.The ultimate bearing capacity of asphalt mixture,the energy consumption change law during loading process and the stress peak value when the specimen first cracks are analyzed.The influence of pore characteristics on the resistance of asphalt mixture is considered to be a twophase composite composed of asphalt mortar and space.The digital specimen containing voids is generated by the same idea as random aggregate.The effect of void characteristics(void ratio,void diameter,void distribution)on the fracture of asphalt mixture is studied by virtual fracture test The evaluation index used is consistent with the effect of aggregate properties.The main results are as follows:(1)The aggregate characteristics will affect the fracture performance of asphalt mixture to a great extent.From the results of virtual fracture test,the increase of aggregate content and aggregate roundness has a negative impact on the fracture performance of asphalt mixture.The influence of aggregate gradation and aggregate particle size on the fracture performance of asphalt mixture is more complex,and its influence presents a wave like fluctuation From the current research,the main reason for the impact of aggregate on the low-temperature fracture performance of asphalt mixture is that the aggregate will change the crack path.Due to the cohesive force element model adopted in the virtual fracture test,the fracture energy largely depends on the failure deletion on the fracture path.(2)The more obvious these characteristics are,the worse the fracture performance is.One of the main reasons is that the voids will change the stress distribution in the specimen,and the other is the effect of void fraction.