The Analytical Solution And Application Of Viscoelastic Multilayered Structures Subjected To Asymmetric Vertical Load

Asphalt pavement design methods are mechanics- empirical methods based on the multilayered elastic system subjected to double circular uniformly distributed vertical load. On the one hand, numerous measured tire-surface ground pressure and numerical simulation show that tire ground pressure is not a typical form of circular uniformly distributed load, and ground load form is associated with the tire pressure and load. Adopting circular uniformly distributed load cannot fully reflect the mechanics response of pavement structure under load. On the other hand, Asphalt mixture is a typical viscoelastic material which performance will change with the loading time or environmental temperature. Therefore, this paper builds the axisymmetric load, adopts Huet constitutive model to describe the asphalt mixture viscoelasticity, and then analysis of axisymmetric loads and material performance on the influence of pavement structure.Focusing on the above-mentioned problems, this paper derived the equations of mechanical response of the elastic half- pace under asymmetric vertical load based on the general solution of multilayered elastic system and the conditions of surface load form and infinity. Based on the measured results, get the mechanical response expressions of elastic half-space under the hyperbolic paraboloid and elliptic load. Then write the programs and analysis of surface vertical strain distribution of elastic half-space body under different loads. The results show that the vertical strain of subgrade surface is equal under uniformly distributed load, when the strain is the largest in load circle center and decreases along radius direction under elliptic load, and the strain are minimum, increases long the radius direction gradually under hyperbolic paraboloid load.Secondly, combining with the condition of double continuous interlayer combination, derived the formulas of mechanical parameters, and then analysis the distribution of pavement structure mechanics response under different loads. The results show that the first principal stress, the first principal strain, the maximum shear stress of pavement structure under elliptic load are larger than the parabolic load and circular uniformly distributed load.Then, combined with condition of multilayered system interlayer combination, adopt coefficient recursion method to derive the expression of load parameters and then get the calculation expression of mechanical response under asymmetric vertical load. Adopting asphalt pavements of semi-rigid base and flexible base as examples, analysis response of pavement structure under three kinds of loads. The results show that the fatigue of asphalt layer and permanent deformation under elliptic load are more adverse. The location of the maximum value of the first principal stress, the first principal strain and maximum shear stress change over timeFinally, analysis accuracy, efficiency and effectiveness of long time calculation and selection of parameters of four kinds of Laplace numerical inversion methods: Durbin, Dubner, FT and FILT. Get the expression of mechanical response of viscoelastic multilayered system subjected to asymmetric load. Analysis permanent deformation evolution process of pavement structure under long-term fixed load and continuous half sine wave load and the mechanical response of pavement structure under different time. The results show that permanent deformation in the load of circle center increases with time going by. Strain distribution of pavement structure change over time, and the stress distribution don’t change one day after.These studies get elastic/viscoelastic mechanics expressions under the asymmetric vertical load, and write computer programs. The results have a certain role in promoting asphalt pavement structure design method.