Axle Load Analysis And Fatigue Life Prediction Of Freeway Asphalt Pavement

With the rapid development of highway in China,The emergence of large,heavy,overload vehicles result in the serious damage of roadbed and pavement.In particular,the damage of roadbed and pavement causing by the cyclic load of traffic flow are more serious.The cyclic load of moving vehicles can lead to the fatigue ruptures of roadbed and pavement which is a serious threat to road safety.The previous researches have got many achievements of the stress and strain analysis,but there are not too much researches analyze the real data and focus on the pavement's fatigue ruptures causing by the real traffic flow which considering the different vehicle,axle and traffic volume.Based on the networking toll data of Henan Province,this paper uses the finite element software ANSYS to simulate and analyze the fatigue life of highway pavement under the actual traffic flow and the law of vehicle axle load.First of all,the thesis introduces the expressway network toll collection system and weighing system.Based on the analysis of the characteristics and composition of the networking toll data of Henan Province,the basic parameters are obtained through the pretreatment and calculation of the data.According to overrun rate,three toll stations are selected as research samples.Secondly,this paper gives a detailed analysis of the traffic situation of Expressway in Henan Province.The basic characteristics of freeway traffic flow are studied from the aspects of traffic volume,vehicle type,traffic volume time distribution and average travel speed of freeway traffic flow.Then vehicle axle load characteristics of expressway are discussed from the aspects of vehicle axle type,axle load spectrum and off axis load.Thirdly,considering the traffic flow of highway vehicles and complex shaft type,the vehicle axle load is converted into equivalent axle,and the equivalent axle development law is summed up,then the future highway equivalent axle scale is predicted.Then the three-dimensional finite element model of the pavement is built,and axle load levels and number of axles of the vehicle's maximum damage track is obtained according to the investigation and statistics of the results.Based on above,the maximum tensile strain of asphalt layer bottom is got under the vehicle average contact pressure,using ANSYS software simulation.Finally,according to the maximum tensile strain of asphalt layer bottom and the prediction of the equivalent axle,the service life of the pavement is analyzed by using the method of fatigue fracture and axle load conversion respectively.