Dynamic Mechanical Analysis Of Asphalt Pavement Based On Cross-anisotropic Properties

At present,road designers in China generally regard road structure as a completely continuous isotropic body,and use the uniform cloth static load in the design process.In fact,the pavement structure layers due to the use of different material and construction technique and other reasons,showing the anisotropic properties.What's more,due to the different materials and the order of construction,the structural layers are not completely continuous.It is well known that the load imposed on the pavement structure by vehicles is not stationary,but moves at a certain speed.Aiming at the difference between the existing design method and the actual situation,the finite element method is used to simulate the pavement structure in this paper.The cross-anisotropy is used to characterize the anisotropy of the pavement structure.A three-dimensional finite element model is established by using moving loads instead of static loads.Then consider the contact between the various layers of the pavement structure and the cross-anisotropy of the pavement structure dynamic response.The main research conclusions were displayed as follows:The cross-anisotropy of AC layer and base has a great influence on the dynamic response of pavement structure,while the cross-anisotropy of subgrade has less influence on the dynamic response of pavement structure.Considering the cross-anisotropy of the pavement structure,the pavement structure deflection,strain of the base bottom and the compressive strain of the top of subgrade is larger than that of the isotropic body.When considering the cross-anisotropy of pavement structure,the longitudinal tensile stress at the bottom of the base is reduced compared with the isotropy.The influence of horizontal load on the longitudinal stress at the bottom of the base and the vertical strain at the top of the subgrade is small,and the vertical strain at the bottom of the AC layer and the shear stress of the pavement structure are greatly affected.It is found that using isotropic to predict the service life by AI method will underestimates permanent deformation and fatigue cracking and overestimates the service life of pavement compared with cross-anisotropy.The contact condition between layers has a great influence on the dynamic response of the pavement structure.There is a superposition effect on the dynamic response of pavement structures considering the contact between layers of pavement structures and the cross-anisotropic Properties.The worse the interlayer contact condition and the smaller the Cross-anisotropy coefficient is,the larger the force index of the pavement structure.Therefore,in the construction of asphalt pavement,attention should be paid to the contact between the various layers of the structure of the treatment,and the lower AC layer and the base due to the nature of two very different materials,in particular,should be concerned.