Research On The Structure Of Asphalt Pavement With Granular Transition Layer

It can well solve the problem about severe reflective cracking and poor drainage of semi-rigid pavement, with high-quality unbound aggregate with strict gradation and construction as transition layer between asphalt surface and semi-rigid course. In this paper, aiming at the nonlinearity of granular materials, the resilient modulus of unbound aggregate is researched systematically from two aspects of material and structure, and mechanical analysis is performed on asphalt pavement with granular transition layer, adopting the superposition method of multilayer elastic system analysis. Finally, structural design method is proposed and reasonable structure is recommended.The mechanism of granular transition layer on preventing semi-rigid pavement from reflective cracking is analyzed from two aspects of isolation function and dissolving and absorbing strain energy of crack tip. This paper integrate the resilient modulus of unbound aggregate calculated by model for the resilient modulus obtained by repeated dynamic load triaxial tests, and the back-calculation based on the bearing-plate test of test road, and refer to the range of the resilient modulus of unbound aggregate ensured by the design method of asphalt pavement in foreign countries, to suggest the resilient modulus of unbound aggregate, according to the granular mixture type and the horizon in the pavement structure. Adopting the KENLAYER program based the superposition method of multilayer elastic system analysis to analyse the nonlinearity for the resilient modulus of granular transition layer, arranging the parameter combination according to the orthogonal design method, performing the range and variance analysis for the result to obtain the factors having the significant influence, and then arranging these factors applying the uniform design method, finally regressing the result and obtain the practical formula. The mechanical analysis is performed on asphalt pavement with granular transition layer, adopting the superposition method of multilayer elastic system analysis and considering the nonlinearity of granular materials. Ascertaining the design indexes that control the destruction of asphalt pavement with granular transition layer are: the tension strain at bottom of asphalt layer, the vertical shear stress on top of granular transition layer, the tension stress at bottom of semi-rigid base and the vertial compressive strain on top of subgrade. The structural design method is proposed and reasonable structure is recommended.