Multi-Scale Algorithm For Predicting Mechanical Properties Of Asphalt Mixture Fracturing Fatigue Damage

At present,the fatigue damage problem of asphalt pavement surface layer is mostly studied in the macroscopic mechanical properties of asphalt mixture.That is,the splitting strength parameters under different fatigue damage conditions are obtained through a large number of laboratory tests,so that the research and numerical simulation of the mechanical properties from the mesoscale are neglected.Therefore,based on AC-13C and splitting fatigue test of asphalt mixture with different particle sizes and its two-dimensional mesoscopic model,the multi-scale algorithm is used to predict the residual stiffness strength parameters of asphalt mixture during fatigue damage process.The main research contents are as follows:Firstly,AC-13C and equivalent bases AC-9.5,AC-4.75,AC-2.36,AC-1.18 are designed and prepared according to the principle that the aggregate mass ratio of each grade is constant and the ratio of aggregate total surface area to asphalt dosage is unchanged.Through the split test and splitting fatigue test of each test piece,the residual strength parameters of splitting under different fatigue damage conditions are obtained.The distribution of aggregates in different specimens under different degrees of fatigue damage is obtained through the combination of CT scanning and digital image processing technology.The statistical randomized probability distribution of random aggregates is introduced into Abaqus to establish two-dimensional detail of different scales.Then,based on the multi-scale algorithm,the algorithm program for calculating the stiffness parameters of the asphalt mixture specimen is selected,and the corresponding calculation scale region is selected.Taking the stiffness parameter of AC-1.18 asphalt mixture as the initial value of iteration,the multi-layer iteration is used to predict the stiffness parameters of the specimens under different fatigue damages after homogenization,and the convergence of the stiffness parameters of fatigue specimens in each specimen is given.Futhermore,based on multi-scale algorithm and finite element numerical simulation test,a multi-scale numerical experimental calculation method for macroscopic splitting strength parameters of asphalt mixture with different particle sizes is proposed.The splitting strength parameters of the next particle size model were predicted by multi-layer iteration by simulating the splitting test,and the splitting strength parameters of all homogenized specimens are obtained,and the attenuation law of the splitting strength with different fatigue damage is analyzed.Finally,the splitting strength parameters predicted by multi-scale numerical test method are compared with the splitting strength parameters obtained by indoor splitting fatigue test,and the effectiveness and feasibility of the algorithm are illustrated.