Multiscale Analysis Of Viscoelastic Response Of Asphalt Pavement Under Coupled Temperature-stress Fields

Asphalt mixture is a typical particulate-filled composite material.In engineering practice,in order to simplify the pavement analysis and design procedures,it is usually regarded as a homogeneous material and analyzed by macromechanics methods based on the phenomenological theory.This method can effectively predict the overall mechanical behavior of the asphalt pavement under given simple conditions,but it cannot fully consider the influence of the heterogeneity of the asphalt mixture and its mesostructure characteristics on the overall mechanical and thermal properties of the pavement.Therefore,there are obvious deficiencies in explaining the microscopic damage evolution mechanism of asphalt mixtures.In response to this problem,this study established a three-dimensional multiscale viscoelastic mechanical response simulation method of asphalt pavement considering the coupling effect of temperature-stress dual field.This method can objectively and reasonably reflect the coupling effect of asphalt pavement under wheel load and external environment.The distribution characteristics of the mechanical response.The specific research work of this article is summarized as follows:(1)In order to accurately characterize the three-dimensional mesostructure and morphology characteristics of asphalt mixtures,and lay a good model foundation for the establishment of a multi-scale analysis method of asphalt pavement mechanical response,this study uses technical means including X-ray CT scanning,image processing and threedimensional reconstruction to established a finite element model of the three-dimensional mesostructure of the asphalt mixture.In order to compare the capabilities of the threedimensional mesoscopic model and the two-dimensional mesoscopic model in simulating the overall thermal and mechanical properties of asphalt mixtures,this study introduces two modeling methods for the two-dimensional mesostructure,namely image processing and random aggregate law.The mesoscale model established by the above three methods was used as the representative volume unit of the macro-asphalt pavement.The complex modulus of the asphalt mixture at different temperatures and loading frequencies was predicted,and the predicted results were compared with the experimental data.The analysis results show that the dynamic modulus and phase angle prediction results of the three-dimensional model are closer to the experimental values than the two-dimensional mesoscopic model,which proves the superiority of the three-dimensional mesoscopic model in simulating the viscoelastic mechanical behavior of asphalt mixture.(2)Considering the significant influence of the periodically changing temperature field and thermal stress inside the asphalt pavement structure on the mechanical response distribution of the asphalt pavement structure,a simulation method for the mechanical response of the asphalt pavement considering the simultaneous coupling effect of the temperature-stress dual field is established.Firstly,based on the principle of heat transfer and measured meteorological data,an analysis model of the temperature field of the asphalt pavement was established to simulate the temperature distribution characteristics of the pavement structure under different meteorological conditions.On this basis,the thermal stress analysis model of the asphalt pavement is established by the sequential coupling method,and the model is used to analyze the change law of the internal temperature stress of the semi-rigid and flexible base pavement structure with time and depth.Finally,through the finite element restart analysis,an analysis model of the mechanical response of the asphalt pavement considering the coupling effect of environmental load and wheel load is established.The results show that the established model can effectively simulate the mechanical response distribution characteristics of asphalt pavement under the simultaneous coupling of multiple factors and the full temperature range.(3)In order to make up for the deficiencies of the single macroscale analysis model based on the phenomenological theory,and fully consider the impact of the mesostructure characteristics of the mixture on the mechanical response and damage evolution of the pavement,this study considers the above-mentioned asphalt pavement mechanics considering the simultaneous coupling of temperature and stress.The response simulation method is combined with the multi-scale analysis method to establish a three-dimensional multi-scale mechanical response finite element simulation method of asphalt pavement considering the coupling effect of temperature-stress dual field.This method considers both the up-scaling linkage mechanism from mesoscopic model parameters to macroscopic model parameters and the down-scaling linkage mechanism of temperature and mechanical response transfer from the macroscale to the mesoscale,so that the relationship between macroscopic and mesoscopic scales can be combined.The mechanical behavior is effectively linked.The results show that the three-dimensional multiscale mechanical response simulation method of asphalt pavement established in this paper can objectively and accurately reflect the mechanical response distribution characteristics of asphalt mixture on the macroscopic and mesoscopic scales under the coupling action of traffic load and environmental factors.The research results of this paper can provide an effective way to further study the damage evolution mechanism of asphalt pavement under service conditions.