Mechanism Analysis And Prediction Of The Rutting And Surface Crack For Asphalt Pavement

With the increase of investment in infrastructure in China,the pavement service life has because longer and longer due to the application of more durable pavement materials and structures and more sophisticated construction technology.Recently,the service life of the main structure of high-grade pavement in some provinces generally exceeds the design life of fifteen years.Corresponding to the increasing service life of asphalt pavement,the maintenance work for the existing pavement will gradually replace the design and construction of the new pavement,becoming the core of the future pavement engineering.However,the research on the mechanism analysis and prediction of pavement surface distresses that affect the maintenance work is insufficient.In order to improve the prediction models for surface distresses,the more accurate mechanical response of asphalt pavement will be calculated through tensioncompression asymmetric viscoelasticity,and the more accurate distributions and evolutions of permanent deformation and damage of pavement will be obtained through viscoplastic damage model.Firstly,two modes of tension-compression asymmetric viscoelasticity based on the direction of total stress and the direction of stress increment are proposed.Through the uniaxial tension and compression creep-recovery tests,the asymmetric models of the two modes are calibrated.The compresions of the two models show that the stress-increment-dominated asymmetric viscoelasticity has the accuracy advantages for the distresses evolution calculation.In addition,the anisotropic-yield,anisotropic-hardening and nonlinear damage model of asphalt mixture is established based on the yield theory of concrete materials,the flow law of nonNewtonian fluid and the continuous damage theory.In order to calibrate the visco-plasticdamage model,the stress-state parameters and plastic potential function parameters of asphalt mixture are determined through stepwise loading uniaxial tension and compression tests.Besides,an improved multi-stage creep-recovery test is proposed to calibrate the viscoplastic strain magnitude parameters,cohesion parameters and nonlinear damage parameters.Secondly,the numerical methods of the tension-compression asymmetric viscoelastic model and viscoplastic damage model of asphalt mixture are derived,and the numerical implementation is realized by compiling the user material subroutine UMAT of the finite element software ABAQUS.In order to make the temperature conditions of numerical calculation closer to the field condition,the measured pavement temperature data from the Research Institute of Highway MOT Track(RIOHTRACK)was characterized and further established into a temperature field model.Meanwhile,the Tireview software developed by Texas Transportation Research Institute was used to analyze the characteristics of tire-road interaction,and a load field model was established based on it.Afterthat,the constitutive models of asphalt mixture,the nonlinear temperature filed model,the nonlinear traffic load model and the pavement structures will be coupling calculated through ABAQUS.The pavement mechanical responses calculated by tension-compression asymmetric viscoelastic model,normal viscoelastic model and linear elastic model were compared and the measured mechanical responses obtained from RIOHTRACK were used to verify the calculation accuracy of the asymmetric viscoelastic model.Finally,based on the distribution of maximum cohesion and yield stress under different structure and load conditions,the structural stabilities and disease development regions of flexible pavement and semi-rigid pavement were analyzed.Through the long-term calculation,the rutting evolution and distribution of flexible pavement and semi-rigid pavement and the evolution of road surface damage were determined.On this basis,by calculating the changes of pavement viscoplasticity and damage under different temperature and load conditions,the influence of different factors on the development of rutting and road surface damage is obtained.The structural stabilities of semi-rigid pavement and flexible pavement were analyzed from the mechanical method,and the basic design principles of two types of asphalt pavement are determined.Based on the research on the evolution of permanent deformation and surface damage,the Initiation mechanism of surface cracks and the relationship between rutting and surface cracks are revealed,which provides an important reference for the pavement maintenance plan and maintenance time.The research on the influencing factors of the rutting and damage evolution provides an important basis for road management schemes.