Dynamic Axle Load Conversion Of Asphalt Pavement Under Complex Driving Conditions Considering Variable Temperature Viscoelastic

In existing asphalt pavement design, the vehicle load is simplified as double-circle uniform load. The dynamic behavior of the vehicle load and the viscoelastic characteristics of asphalt concrete were ignored. Although the current code for urban road design regard asphalt layer shear stress as an index of design, but it still follow the axle load conversion formula of asphalt pavement deflection and bending tensile stress layer bottom in highway design specification. This method is deficient. Rigid asphalt pavement dimensional numerical model is established in this paper. Analyzed the dynamic response of asphalt pavement which is subjected to moving load and the influence of temperature field of asphalt concrete viscoelastic parameters were considered. The dynamic axle load conversion formula was presented based on the flexural tensile stress and shear stress index.Firstly, the effectiveness of the numerical calculation was verified based on two-dimensional Lamb problem and damping parameters are made comparison. Three-dimensional dynamic numerical model of asphalt pavement with rigid base was established which under double circular uniform moving load. Effects of speed, road surface friction coefficient and axle load were analyzed. The dynamic axle load conversion formula considering the friction coefficient and the bottom of the asphalt layer tensile stress was calculated.Secondly, the effectiveness of pavement temperature field numerical calculation was verified. The temperature experiment of rigid base asphalt pavement has carried out and a numerical model with the same conditions has established for temperature field simulation. Analytical results were fit well with test data. The calculation results can provide effective data for the fifth chapter to analysis asphalt material viscoelasticity under nonconstant temperature state.Thirdly, a three-dimensional dynamic numerical model of tire-pavement structure was established. Tires' structures are complex, so the tire was reasonably simplified. Radial tire model was established with Hypermesh and AutoCAD. The elastic parameters of the asphalt concrete were defined as a function of temperature through the VUMAT user subroutine. And then the three-dimensional dynamic numerical model of tire-pavement was established in ABAQUS.Finally, the effect of dynamic response of asphalt pavement under non-uniform moving load with different acceleration and deceleration was analyzed. Dynamic numerical analysis of asphalt pavement was carried out combined with the intersection vehicle starting and braking speed experiment and asphalt variable temperature viscoelastic. A dynamic axle load conversion coefficient based on shear stress of asphalt layerwas proposed to make up for the inadequacy of existing specifications.