Dynamic Response Of Asphalt Pavement With Crack And Overlay Structure Under The Vehicle Load

Cracks on asphalt pavement is a major form of early pavement damage,which has attracted common attentions.Aiming at the the cracks on asphalt pavement,this paper takes a overall consideration of factors including the vehicle load,the vehicle speed,temperature,and the characteristics of asphalt mixture,researches the damage mechanism of cracked asphalt pavement under different circumstances,and further studies a reconstruction method of overlaying an asphalt concrete layer and a stress absorbing layer onto the old pavement.With the ABAQUS---a large finite element analysis software,this paper builds a three-dimensional viscoelasticity model of typical asphalt pavement structure,researches the pavement crack extension regularity when a vehicle is running at constant speed and braking,and builds a viscoelasticity model of cracked asphalt pavement,makes a comparison between the responses of pavement structures when the vehicle is running at constant speed and braking on the overlaid pavement.Firstly,the characteristics of viscoelastic materials,the viscoelastic mechanical constitutive model of asphalt material,the time-temperature superposition principle and the basic principles of fracture mechanics are introduced in this paper to provide theoretical basis for building,calculating and analyzing a crack model.Secondly,the parameters of asphalt pavement materials are decided,the three-dimensional viscoelasticity model of asphalt pavement when the vehicle is running at constant speed is established,and the influence of vehicle load,vehicle speed and vehicle temperature stress to stress intensity factor,J integration,road surface deflection and asphalt bottom layer tensile stress(S33)are analyzed.Thirdly,a viscoelasticity model of cracked asphalt pavement with braking load is built,and a comparison between the pavement crack extension regularities is made when the vehicle is running at constant speed and braking.Finally,the old pavement is overlaid with an asphalt rubber stress absorbing layer and an asphalt concrete pavement,a comparison between the mechanical response of the original pavement structure and overlaid pavement structure is made when the vehicle is running at constant speed and braking.Pavement overlaying can restrain the crack stress concentration effectively and reduce the occurrence of transverse cracks when the vehicle is breaking.A better restraint effect would be achieved if the vehicle runs at constant speed.