Asphalt Pavement Structure Design On Expressway Implementation And Inversion

The structural Design of Asphalt Pavement is one of the most important areas of the Asphalt Pavement research, which has been done both home and abroad. The areas mainly concentrate in the applicability of the pavement structure under different economic conditions, natural conditions, traffic types and traffic loads. However, in this paper, the research is about the formational process of the structure from the construction aspect.During the construction process, the distinctions of the weather, construction processes, road materials and material compositions deeply affect the variations of the deflection values, CBR values, and thickness of pavement layers, compressive modulus and bending modulus of the subgrade. These changes definitely differ from the road stress distributions and stress intensity of the original design, and the service life of the pavement. The main purpose of this paper is to research the relationship between the variations and internal stresses during the construction process and the service life of the pavement.Firstly, subgrade research: Assuming the thickness and the compressive modulus of the pavement cushion and that of the base course as the original setting, with the potential deflection values of the subgrade, the stresses of subgrade and pavement layers were confirmatorily calculated by using the standard axle load BZZ-100, then the service life of the asphalt pavement was invertedly calculated and the related graphs were drawn.Secondly, cushion research: based on the thickness and the compressive modulus of the cushion, assuming the deflection values of the subgrade and the thickness and compressive modulus of the other pavement layers as the designed setting, the stresses of subgrade and pavement layers were confirmatorily calculated by using the standard axle load BZZ-100, then the service life of the asphalt pavement was invertedly calculated and the related graphs were drawn.Thirdly, other layers research: presetting the thickness and the compressive modulus as variables and assuming the deflection values of the cushion and the thickness and compressive modulus of the other pavement layers as the designed setting, the stresses of subgrade and pavement layers were confirmatorily calculated by using the standard axle load BZZ-100, then the service life of the asphalt pavement was invertedly calculated and the related graphs were drawn.Finally, in summary, the relationship between the changes of the actual pavement structure after the construction and both the inner stresses of asphalt pavement and the anticipative service life of the pavement was summed up, and the related function was built.Based on those above, the model which simulates the actual pavement structure variables, stresses and anticipative service life was established.Considering a certain expressway as a object of study, the stress intensity of the pavement structure after construction and the anticipative service life of the pavement was figured out. In the subgrade study, assuming the thickness and the compressive modulus of the pavement cushion and that of the base course as the original setting, according to the actual deflection values, the stresses of subgrade and pavement layers were confirmatorily calculated by using the standard axle load BZZ-100, then the service life of the asphalt pavement was invertedly calculated. While in the cushion study, based on the deflection values of the subgrade and both the thickness and the compressive modulus of the cushion that was actually measured, assuming the thickness and compressive modulus of the layers over the cushion as the designed setting, the stresses of subgrade and pavement layers were confirmatorily calculated by using the standard axle load BZZ-100, then the service life of the asphalt pavement was invertedly calculated. Successionally, in the other layers study, considering the thickness and the modulus of the layers beneath the related layer as actually measured setting, while that of the layers over the related layer as designed one, the stresses of subgrade and pavement layers were confirmatorily calculated by using the standard axle load BZZ-100, then the service life of the asphalt pavement was invertedly calculated; as it was computed eventually to the topside, the actual service life after the build-up of the pavement was figured out, then according to the figured-out service life of the pavement in the confirmatorily calculation above, the related graphs of the service life were drawn.