Determination Of Viscoelastic Constitutive Parameters Of Asphalt Mixture And Analysis Of Viscoelastic Damage Of Asphalt Pavement

The ultimate goal of mechanical analysis of asphalt pavement is to predict the performance of the pavement,and use this as a basis for pavement structure and material design.The main factors affecting the performance of the road surface include fatigue cracking,rutting,water damage and surface damage.This article mainly applies the principle of fatigue damage mechanics to analyze the fatigue cracking of asphalt pavement.To realize the mechanical analysis of pavement fatigue cracking,there are two important prerequisites:one is to select an appropriate viscoelastic constitutive model and accurate model parameters to analyze the viscoelastic response of the pavement;The second is to select an appropriate fatigue damage evolution model to analyze the fatigue damage process of the road surface.At present,the main method for determining viscoelastic constitutive parameters is the fitting method.This method has multiple solutions,and the calculation parameters are generally determined by relaxation tests or creep tests.The test variables are not easy to control,and the calculation results have a large discreteness.In view of the above situation,this paper firstly proposes a transformation method to determine the constitutive parameters of the Burgers model based on the basic theory of linear viscoelasticity and the extreme value characteristics of the dynamic modulus of asphalt mixtures,and adopts laboratory tests,theoretical analysis and numerical calculations verify the effectiveness of the conversion method.Secondly,using the viscoelastic parameters of the mixture determined by this method,the numerical calculation of the viscoelastic response of the airport asphalt pavement is carried out.The numerical calculation results are compared with the field measurement and representative viscoelastic calculation software(Flexpave),which proves the validity of the viscoelastic parameter conversion theory and the viscoelastic response calculation method given in this paper.Finally,according to the obtained accurate viscoelastic constitutive parameters,combined with the fatigue damage evolution model of asphalt mixture,the damage evolution process of asphalt pavement under vehicle load is analyzed.A three-dimensional pavement structure model was established by finite element software,and the above-mentioned parameter determination method was used to simulate the damage development process of the asphalt pavement.The pavement damage rate is calculated and compared with the actual pavement damage rate,the development law of fatigue damage of the asphalt pavement is analyzed,and the accuracy of the calculation results is verified.The research results provide a relatively accurate calculation method for determining the viscoelastic parameters of the Burgers model,make the viscoelastic response analysis results of asphalt pavement more in line with the actual situation,and provide a reference for the analysis of the actual pavement viscoelastic damage development process.