Creep Damage Of Asphalt Concrete Pavement Structure Research

With its good performance, asphalt pavement has been widely used in road construction. Although it has many advantages, but the road will produce different degrees of damage during the construction phase, the operational phase, and maintenance process. As the damage continue cumulative, the damage of pavement structure will be more serious, resulting in reduced bearing capacity of the pavement structure, accelerating destruction of the pavement structure, reducing its remaining life. to a certain extent, caused a loss for the country, so it is necessary to find out evolution of injury and impact to its internal force.In this paper, based on the viscoelastic theory and damage mechanics, deduced creep damage constitutive model of asphalt mixture. Using the finite element software ABAQUS build three-dimensional model to study the mechanical response with damage and no injuries. In this process, the main problem is how to determine the form of the damage variable, how to couple damage field to the constitutive relation of lossless material. Finally, creep damage constitutive model was pushed out.In summary, this paper carry out research and get the relevant conclusions for the following aspects:(1)By reading a lot of relevant literature, The existing viscoelastic theory and damage theory are summarized and analyzed. From the literature to find more suitable for asphalt mixture viscoelastic constitutive equation. theory to identify more suitable for asphalt viscoelastic constitutive equations from the literature, and then using the continuum damage mechanics theory and strain equivalence principle to determine the damage variable, which can reflect the deformation of the asphalt mixture. And deduces the creep damage constitutive model of the constitutive equation.(2)According to the ABAQUS user manual, develope user material subroutine UMAT of creep damage model in FORTRAN language, so that subsequent finite element analysis.(3)To verify the accuracy of the creep damage model and the UMAT subroutine, based on the finite element numerical analysis method, through the UMAT subroutine interface put creep damage constitutive into the ABAQUS main program. Build the three-dimensional finite element model of experimental module. Comparison of the results of damage and no injuries to the results of static load uniaxial creep test.(4) Build a three-dimensional model of asphalt pavement. Use the finite element asphalt to calculate its internal forces under different loads and different temperatures to study the different response in the case of damage and no damage. From the numerical results we can know that whether transformation temperature or load, without regard to injury, the equivalent creep strain appears only two stages. At the beginning, the equivalent creep strain increases with time, and then become almost a horizontal line. It shows the effect of consolidation. This is not realistic. When considering the damage, the curve of modified Burgers creep damage model in this paper can simulate the results of the three stages of creep asphalt mixture. As the load increases and the temperature rises, the failure time is getting shorter. We also found that there is a certain relationship between the damage value with the equivalent creep strain and the vertical displacement. And fit by relatively high precision relationship by Origin8.0. Provide some reference for the study of further damage.