Study On Constitutive Equation Of Viscoelastic Plastic Asphalt Mixture And Its Application

The transportation infrastructure in China has been developing rapidly,especially in road construction.About 95% of the road surface is made by asphalt pavement.As the development of society and economy,the traffic flow and heavy traffic volume of highway pavement are greatly increased.The new road's surface is affected by severe cold,saline-alkali,high temperature,freezing thawing cycle and so on.The failure of the asphalt pavement is more serious in China,especially in the rutting caused by permanent deformation,has caused serious harm to road traffic safety.At present,the most important constitutive relation for describing the mechanical properties of asphalt mixture is still in the theoretical study stage.Although many scholars have put forward a large number of theoretical models,most of the models still remain in the elastic and viscoelastic stages,and the methods for the viscoelastic and viscoplastic analysis of asphalt mixtures are very less.Therefore,based on previous studies,a new viscoelastic viscoplastic constitutive relation of asphalt mixture is developed.And after that,it is applied to the finite element method.Firstly,the basic mechanical concepts,such as creep and relaxation,are introduced.Then,several rheological viscoelastic plastic models of asphalt mixture are present.The two basic theories commonly used in the constitutive relation of asphalt mixture have been suggested: the principle of linear superposition and the principle of time temperature equivalence,and then the basic concepts of UMAT in ABAQUS is recommended.Secondly,the one-dimensional theory of generalized Maxwell model is adopted and extended to three dimensional.By using the incremental stress-strain relation and combining with the Perzynas model,a new constitutive relation of viscoelastic plastic constitutive relation of asphalt mixture is developed.Using the method of separating parameters,the viscoelastic and viscoplastic data are separated from the experimental data,then the relevant parameters are fitted respectively.According to the time temperature equivalence principle and the creep test curve of the asphalt mixture,the time temperature conversion factor is fitted.After that,the viscoelastic viscoplastic model of asphalt mixture is verified in ABAQUS through the UMAT.Finally,the asphalt pavement model is established,and the model is used in the ABAQUS to simulate the permanent deformation of the asphalt pavement.and the permanent deformation of the asphalt pavement under different time,different speed and different loads is discussed.It is concluded that asphalt pavement is most prone to permanent deformation under heavy load and low load.