Mechanical Response Analysis Of Viscoelastic Asphalt Pavement Considering Cross-anisotropy

Asphalt mixtures are typical viscoelastic materials,and unbound aggregates bases(UAB)and soil subgrades are obviously cross-anisotropic,therefore the asphalt pavement structure design and analysis based on isotropic layered elastic theory has obvious limitations.In this paper,the mechanical response of the viscoelastic asphalt pavement structure considering the cross-anisotropic characteristics of unbound aggregates bases and soil subgrades under the static load and the FWD impact load is analyzed theoretically,and the analytical stiffness matrix solution is established respectively.Then the mechanical response of the viscoelastic asphalt pavement considering the cross-anisotropy of the UAB is calculated and analyzed for specific problem.This article launches the research from following aspects:(1)Starting from the basic equations of isotropic viscoelastic and cross-anisotropic elastic axisymmetric spatial static and dynamic problems,and the basic control equations are obtained,then the corresponding integral transformations are employed to get stresses and displacements components of static and dynamic problems in the integral transformation domain.(2)Combined the Cauchy stress principle and the concept of stiffness matrix,the layer-element stiffness matrixes of the finite layer(asphalt layer)of the isotropic viscoelastic axisymmetric spatial static and dynamic problem,and these of the finite layer(asphalt layer)and half-space(subgrade)of the cross-isotropic elastic axisymmetric spatial static and dynamic problem are developed respectively on the basis of the proposed stresses and displacements components.The global stiffness matrixes are assembled by matrix matching method of FEM,and then the analytical stiffness matrix solution of the static and dynamic problems in the integral transformation domain are obtained.Finally,the corresponding integral transformation numerical inversion method is utilized to obtain the solution in the physical domain.(3)In order to verify the accuracy of the analytical solution in this paper,we first reduce the analytical solutions of the viscoelastic static and dynamic problems of viscoelastic asphalt pavement considering cross-anisotropy to elastic problem and isotropic problem respectively,and then compared them with the existing analytical solution.Furthermore,the proposed static and dynamic analytical solutions are compared with the FEM simulation respectively.The results of comparison show that the static and dynamic analytical solutions are of high accuracy.At the same time,in the process of comparison,the analytic solution of this paper demonstrate more practicability than FEM.(4)The results show that the mechanical responses of the viscoelastic asphalt pavement considering the cross-anisotropy of the UAB reveal obvious characteristics of viscoelastic material,and the cross-anisotropic properties of the UAB have significant effects on the pavement mechanical response.The research of this paper can better characterize the mechanical behavior and damage mechanism of the pavements under the loads,which is of great significance to improve and enhance the pavement design theory.