Micro-mechanical Analysis Of High Modulus Asphalt Pavement Structure Under Load

Asphalt mixture is a kind of pavement material widely used in road engineering,it is anisotropic polyphase composite material.The finite element generally regards asphalt mixture as a homogeneous material.The phenomenological study is carried out from the macroscopic view,but the internal meso-structure of asphalt mixture is neglected,and it is difficult to reveal the characteristics of the stress and deformation of the internal meso-structure.Therefore,the asphalt mixture is regarded as the three-phase material of aggregate and mineral material,asphalt and the boundary between them,and the asphalt pavement structure model is established.From the microscopic view,the mechanical characteristics of pavement structure under static load and dynamic load are studied.Firstly,the suitable semi-rigid base asphalt pavement structure is chosen,and the indoor uniaxial compression test of each layer of pavement material was carried out,and the axial stress-strain curves were obtained.Secondly,using particle flow discrete element software PFC2 D randomly generated each layer of pavement materials,and the numerical model of uniaxial test was established.By constantly adjusting the micro-parameters,the test result of the axial stress-strain curve are in agreement with the numerical simulation result of the stress-strain curve,and the influence of particle micro-parameters on the macroscopic mechanical characteristics of asphalt mixture is analyzed by parallel bond elastic modulus,friction coefficient,bonding radius and bond strength of parallel bond.Finally,the structure model of high modulus asphalt pavement and normal asphalt pavement structure model are established based on the identified micro-parameters of each layer.In the high modulus asphalt pavement,the middle layer is set to the high modulus layer,and in the normal asphalt pavement,the middle surface layer is the same material as the upper layer.The differences between the two kinds of pavement structures in the distribution of contact force,the display of force chain,displacement(deformation),tension and compression stress,and shear stress are simulated under static load.The analysis shows that under the action static load,the middle layer is set as a high modulus layer which can effectively improve the stress state of asphalt pavement,reduce the deformation of pavement,and improve the anti-rutting performance of asphalt pavement.On the basis,the meso-characteristics of the two kinds of pavement structure under the action of dynamic load is simulated,including deformation,tension and compression stress,shear stress distribution and so on.