Study On Rutting Prediction Model Of Asphalt Pavement Considering Temperature And Stress Changes

With the increase of traffic volume year by year,many asphalt pavements have been damaged by rutting to varying degrees within a few years of construction,which seriously affects the service quality of the road.The current specification takes the rutting depth as a control index for pavement design and proposes a permanent deformation prediction model of the asphalt layer based on the mechanical experience method,which is of great significance for the prevention and control of pavement rutting.However,the consideration of stress in this model is too simplified.Usually,only the dynamic modulus of asphalt mixture at 20℃ is used to calculate the vertical compressive stress of each layer,which is obviously different from the actual stress condition of the pavement.Under the coupling effect of temperature and load,the stress field of the pavement is actually in a state of constant change.Therefore,when establishing the rutting prediction model,the characteristics of the pavement stress changing with temperature should be fully considered,so as to achieve the purpose of reasonably predicting the rutting.A study on rutting prediction of asphalt pavement considering temperature and load was carried out,including the following aspects:(1)The temperature field model of the asphalt pavement was established by finite element method,and the change rule of the internal temperature of the pavement under the meteorological conditions of high temperature representative days and medium and high temperature months in Changsha area was analyzed,and the reliability of the numerical simulation results was analyzed according to the measured data of the temperature field.(2)According to the dynamic modulus prediction model and the simulation results of the temperature field,the variation characteristics of the modulus field in the middle and high temperature months in Changsha area were analyzed.Then,an asphalt pavement model is established by finite element,and the modulus field data at different times are imported into the model respectively,and the variation law of the stress field of the asphalt pavement is analyzed,and the vertical compressive stress correction factor is proposed.stress is corrected.(3)Triaxial dynamic creep test was carried out to analyze the permanent deformation law of asphalt mixture under different temperatures,different load sizes and different loading times,and combined with the standard rutting test,the initial rutting prediction model was determined.Then the vertical compressive stress correction factor is introduced into the initial rutting prediction model,and a rutting prediction model of asphalt pavement considering temperature and load is established.(4)Based on the principle of equivalent damage,determine the equivalent temperature and equivalent compressive stress correction factor of each layer of asphalt pavement in the middle and high temperature months in Changsha area.Secondly,the prediction model is used to calculate the rutting depth of the pavement based on the project,and combined with the measured data of the old road core samples,the contribution rate of the pavement rutting is analyzed.Finally,a layered design method of asphalt mixture high temperature performance index is proposed,and according to the rutting prediction model in this paper,the proposed value of dynamic stability of asphalt mixture at each layer is deduced,and the relationship between asphalt mixture design and asphalt pavement design is established.Maximize the benefits of pavement design.