Study On Test And Pavement Response Of Semi-rigid Base Asphalt Pavement Material Transversely Isotropic

In the construction of high-grade highway in our country,the most of highway is the semi-rigid base asphalt pavement.In many roads have been built,the pavement diseases were occurred prematurely,the road conditions was affected,the service life of pavement was greatly shorten,the pavement maintenance and repair costs were increased.Asphalt mixture and semi-rigid base material is a typical composite material in our country.Due to the original anisotropy of the composite material caused by the material properties,as well as the process of secondary anisotropy caused by mixing rolling paving in the construction process,asphalt mixture and semi-rigid base material is anisotropic.However,in China's existing asphalt pavement design theory,the pavement material is still regarded as isotropic,which obviously can't be reflected the real state of the mixture.And a lot of research shows that,considering the material anisotropy,the pavement structure design is dangerous.Therefore,combined with experimental research and mechanical analysis,the semi-rigid basement asphalt pavement dynamic response was studied in this paper.Based on the uniaxial compression test and the splitting test,the compressive elastic modulus and the indirect tensile strength of semi-rigid base material and asphalt mixture were studied.Based on the compressive modulus and indirect tensile strength,the influence of temperature and gradation composition on the transversely isotropic properties of asphalt mixture was analyzed.The effects of inorganic binder type,inorganic binder content and gradation composition to the semi-rigid base material were evaluated.The results show that the vertical compressive modulus of asphalt mixture and semi-rigid base material is larger than that of horizontal compressive modulus,but the vertical indirect tensile strength is less than the horizontal tensile strength.As for the asphalt mixture,as the mixture of ore material particle size increases,the degree of anisotropy is gradually increased,and 20? asphalt mixture compressive elastic modulus anisotropy degree is more obvious;As for the semi-rigid base material,the anisotropy of the skeleton is much larger than that of the suspension compact structure.The larger the inorganic binder content is,the smaller the anisotropy of the mixture is.Secondly,based on the transversely isotropic theory and experimental data,combined with the Nan-Yue Highway east extension project,the pavement structure was established,the three-dimensional finite element model of the pavement was established,the mechanical calculation was carried out,and the dynamic response of the transversely isotropic and isotropic pavement was analyzed.The results show that considering the transversely isotropic characteristics,the vertical deformation of the pavement structure is too large,and the structural design is biased towards danger.Finally,by changing the thickness of the grass-roots structure layer,the influence of the study layer thickness on the transversely isotropic pavement mechanics index is analyzed.