Study On Rutting Prediction Model And Deformation Mechanism Of Asphalt Pavement Based On Full-Scale Test Loop

Asphalt pavement is the main pavement form of high grade highway in our country.As the main disease of asphalt pavement,rutting not only causes damage to pavement quality and durability,but also seriously affects driving safety and comfort.Therefore,it is particularly important to improve the accuracy and universality of asphalt pavement rutting prediction,so as to effectively prevent and control it.Based on a large number of observation data of RIOHTrack from the Highway Science Research Institute of the Ministry of Transport,combined with the accelerated loading test project,four types of asphalt pavement structures were selected to analyze the rutting development law and carry out research on rutting prediction of different asphalt pavement structures.It mainly includes the following aspects:(1)Based on the observation data of the first full-scale pavement test track in China,according to the accelerated loading test conditions and material parameters,four asphalt pavement structures(rigid base,semi-rigid base,flexible base and full-thickness type)were determined as the research objects.The accelerated loading test and periodic detection were carried out.Based on the measured rutting data,the rutting development rules of four asphalt pavement structures were analyzed,the rutting resistance performance of different structures was compared,and the influence of asphalt pavement thickness,base stiffness and load level on the rutting depth was studied.(2)The temperature field research was carried out based on the pavement structure temperature and atmospheric temperature of the full-scale ring road in 2019.The temperature field model based on the full-scale ring road surface structure varies with depth is established.According to the temperature,axle load,driving speed and meteorological characteristics of the full-scale road test loop,combined with the material parameters and structural mechanical response parameters of asphalt mixture,six commonly used rutting prediction models are evaluated.The results show that:The existing rutting model can forecast the rutting development of some asphalt pavement structures in stages,but the overall prediction effect is not good and the applicability is not strong,especially the full-scale ring road semi-rigid base and rigid base asphalt pavement structure,the prediction effect is poor.(3)Based on the formation mechanism of asphalt mixture permanent deformation and the development law of rutting measured in full-scale test loops,a three-stage rutting prediction model for asphalt pavement was proposed,and the ability of the existing rutting models to describe the three-stage permanent deformation behavior of asphalt pavement was evaluated.Puts forward a new stage of asphalt pavement rutting three forecast model and determine the three stages of cut-off point algorithm,are developed on this basis,established the accelerated loading test under the condition of semi-rigid base,rigid base and flexible base asphalt pavement structure of three stage forecast model,can well with different stiffness of asphalt pavement rutting at the grass-roots level to carry on the forecast,The prediction accuracy is more than 90%.(4)Using the finite element software ABAQUS,the creep model of asphalt pavement under continuous changing temperature was established to analyze the change rule of rutting depth and internal response of asphalt pavement structure under different structural combinations(rigid base,semi-rigid base and flexible base asphalt pavement)and different base modulus.It is found that the rutting depth of asphalt pavement with different base stiffness is as follows:flexible base>semi-rigid base>rigid base,which is consistent with the rutting law measured in the full-scale test loop.With the increase of the modulus of the base layer,the compressive stress inside the surface layer and the top of the base layer of the three pavement structures increases gradually.At the same time,the cause of rutting is futher analyzed from the mechanical point of view:the shear stress at 2cm～6cm of asphalt surface is the main factor for the development of rutting on asphalt pavement.The research results improve the accuracy and applicability of the rutting prediction model for asphalt pavement,which can provide reference for rutting prediction and maintenance of asphalt pavement,and can also provide a basis for asphalt pavement with wide stiffness region and long life.