| Current pavement design is based on the static analysis of multilayer elastic system, but the dynamic response and static analysis of pavement structure are quite different, and the asphalt material has obvious strain rate effect. Thus, the research on dynamic response of pavement structure considering strain rate and interface effect is of practical significance, which can provide basis for pavement design.Firstly, based on Abaqus user material subroutine, the VUMAT of viscoelastic constitutive model of asphalt concrete was complied, and Prony series in ABAQUS was used to verify the validity of the VUMAT.Secondly, a confining pressure test method is presented to make that laboratory test parameters can be applied to an actual structure analysis. By adjusting the surrounding and bottom springs’stiffness and friction coefficients between confining pressure plate and specimen, the vertical deformation of laboratory specimen could be close to calculation results of the infinite element boundary specimen. Uniaxial compression tests of standard Marshall samples of asphalt mixture under different loading rates of 0.2 kN/s,0.5 kN/s and 1 kN/s were carried out respectively. Stress-strain curves exhibited the strain rate effect, and the applicability of confining pressure system to the strain rate effect was verified. The feasibility of confining pressure system simulating different support was demonstrated by comparing with the subgrade joint condition.Thirdly, the formula of viscoelastic parameters considering rate-dependent were established to analyze the influence of strain rates on asphalt concrete, and the application on road engineering was also studied. According to stress relaxation tests of asphalt concrete at different loading rates, the formula of Burgers model parameters considering rate-dependent viscoelasticity was obtained and the generality was verified. A user subroutine of the dynamic constitutive model considering rate-dependent viscoelasticity was compiled by Abaqus/VUMAT. Field plate loading tests were respectively implemented on new and 5 years asphalt pavements, and dynamic rebound deformation data of the new pavement and the old pavement with different diseases were obtained. A finite element model of coupling tire and pavement was built, and dynamic responses of asphalt pavement considering the effect of rate-dependent were analyzed.Finally, compaction tests were implemented on the top face of asphalt surface course, cement concrete base and subgrade by Portable falling weight deflectometer (PFWD). The dynamic elastic modulus of each layer was calculated by the field measured data of vertical dynamic deflection and finite element software. A two-dimensional finite element model was built to analysis the influence of interface effect on energy propagation of different road materials. Finite element models with different incident angles and contact layers were established to analysis the transmission phenomenon and distribution characteristics of the stress wave energy through the interface. |
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