Finite Element Analysis Of Semi Rigid Base Asphalt Pavement In Seepage-Stress United Field

Long time exposure under complex environmental conditions, such as rain and snow, and coupled with overload phenomenon more and more serious, the early damage of asphalt pavement is more and more prominent. Tracing rut, pit slot, crack and other diseases of asphalt pavement have appeared. The happening of these diseases not only affect the performance of the pavement, also increase the maintenance cost. It is generally recognized that, dynamic water pressure under vehicle loading is the main factor of early damage of asphalt pavement.In order to study the destructive process of semi rigid base asphalt pavement under the coupling of water and rolling vehicle, the finite element software ABAQUS was used to establish the mathematical model of semi rigid base asphalt pavment and the response in stress-seepage united field was researched.A large number of studies show that the asphalt mixture is a kind of viscoelastic material with the properties of porous and multiphase. The common linear elastic model can not reflect the rheological properties of asphalt material. So assuming the asphalt pavement as a structure of porous medium, effective stress and deformation theory as the foundation, get the viscoelastic constitutive model. The stress field model of asphalt pavement was got by applying a moving load on the model. It analyzed the change rule of vertical displacement, vertical stress, transverse stress, longitudinal stress and shear stress of different layer, studyed the influence of speed and axle load on the response, and compared the results of linear elastic model and visco elastic model. The seepage model was established by using Darcy’s law. It analyzed the change rule of pore water pressure, saturation and settlement of different layer. Then it extracted the limit state stress of pore water pressure, and input the model of stress field as initial stress to joint the stress field and seepage field.The research results show that:(1)At a certain axle load and speed, the response of each pavement layer has the characteristics of volatility and instantaneity, and decreases with the increase of depth of the different structural layers. When improve the speed, all the response of each structural layers decrease except the longitudinal stress. When improve the axle load, all the response of each structural layer increase.It shows the destructive effect of overload on asphalt pavement. The response of linear elastic model is greater than the viscoelastic model, and even results in the distortion. The results calculated by viscoelastic model are more accord with the actual.(2)Under the action of seepage field alone, the changes of the pore water pressure and saturation inside the asphalt pavement are all first increased and then decreased with the extension of the rainfall time. The vertical deformation of the pavement struvture is first uplift, and then settlement. When settlement after reaching the maximum value, the deformation will recover a part, and eventually produce downward vertical settlement.(3)In stress-seepage united field, the response of asphalt pavement is greater than in stress field by contrasting curves of the vertical displacement, vertical stress and longitudinal stress. The response of asphalt pavement is smaller than in stress field by contrasting curves of the transverse stress and shear stress, but its has a larger range. It shows that when there is water, the asphalt pavement produce the structural damage such as cracking and permanent deformation more easily. When speed or axle load improve, all the response of each structural layers increase.(4)It shows that the results are similar by comparing the data from monitoring and modeling. Therefore, this model proves to be reliable.