Study On Asphalt Pavement Structure Of High-grade Highway Under Heavy Traffic Load In Inner Mongolia

With the development of national economy, over-load phenomenon on the main highway is more and more serious in Inner Mongolia as energy output place. The current pavement structure is difficult to meet the demand of over-load driving due to the current Specifications for Design of Highway Asphalt Pavement is based on the regular load. Therefore, the pavement design method, applying for actual traffic conditions, is needed to be studied. In this thesis, truck axle load distribution, load working shape and area and the asphalt pavement disease are analyzed under heavy duty traffic based on entity engineering; the design parameters of pavement material are studied through laboratory test; the mechanical state of asphalt pavement structure is analyzed by finite-element method; the axle load conversion of asphalt pavement under heavy duty traffic is studied; the typical asphalt pavement structure and design method are put forward, which is suitable for heavy duty traffic.Firstly, truck axle load distribution, load working shape and area and the asphalt pavement disease are analyzed under heavy duty traffic. The axle load distribution of heavy-load truck is obtained through analyzing the traffic composition and axle load data of the typical freight transport highway in Inner Mongolia and its around area. The loading shape and working area of heavy-load truck are got through investigating the touching ground area and pressure of tire. China National Highway 110’s pavement disease and forming reasons under heavy duty traffic are got by researching.Secondly, material design parameters of asphalt pavement are studied under heavy load condition. The pavement structure materials’stress-strain curve and dynamic module master curve of asphalt mixture are got via laboratory test and mechanical analysis. The dynamic and statistic module’s range of asphalt mixture and semi-rigid base material are provided for mechanical analysis of pavement structure.Thirdly, the mechanical responses of asphalt pavement structure and its changing trend are analyzed under heavy load. The mechanical responses of asphalt pavement structure under different load are calculated and analyzed using finite element software ABAQUS. The mechanical responses of three kinds of pavement structure, with different bases (flexible base, semi-rigid base, rigid base), are analyzed and compared. The influence of longitudinal slope on asphalt pavement structures’mechanical responses is also studied, and the reason of pavement disease on longitudinal routes is stated. The fatigue model and rutting model of asphalt pavement are amended according to asphalt pavement’s mechanical characteristics on longitudinal routes. The existing pavement structure of China National Highway 110 is analyzed using asphalt pavement fatigue model, rutting model, base fatigue model and subgrade surface compression strain model, and the existing problems are pointed.Fourthly, axle load conversion under heavy duty traffic is deduced. Based on the mechanical analysis, the axle load conversion formula is got according to different forecast model and equivalence principles, including fatigue equivalence, rutting equivalence, subgrade surface compression strain equivalence.At last, the typical structure and design method of asphalt pavement under heavy duty traffic is proposed. The structure and method is proposed primarily based on the study of pavement disease, axle load distribution, load working shape, pavement mechanical analysis, axle load conversion and material parameters. The method is proved to suit for asphalt pavement design under heavy duty traffic condition through specific example.