Rutting Prediction Of Asphalt Mixture Based On Rate-Dependent Thermoelastic Viscoplastic Constitutive Model

With the rapid development of China’s highway industry,some initial asphalt pavements have gradually entered the stage of maintenance due to the influence of various pavement diseases such as rutting diseases.As one of the main diseases of highway asphalt pavement in China,the rutting of asphalt pavement greatly affects the driving safety and driving comfort of highway,and can also cause major traffic accidents in serious cases.The prediction of rutting diseases helps to establish preventive maintenance plans and design repair strategies,delay the occurrence of rutting diseases or timely repair asphalt pavement.Therefore,this paper predicts the rutting deformation of asphalt pavement based on the rate-dependent thermo-elasto-viscoplastic constitutive model.The main work and research conclusions of this paper are as follows:(1)The optimum asphalt-aggregate ratio of AC-16C asphalt mixture is determined to be 4.36%by Marshall test and mix design.Unconfined uniaxial compression tests were carried out at 35℃,45℃ and 60℃ with loading rate of 2mm/min and 35℃ with loading rate of 0.6mm/min,3mm/min and 6mm/min.The test results show that AC-16C asphalt mixture has remarkable rate sensitivity and temperature sensitivity.(2)Aiming at the rate sensitivity and temperature sensitivity of AC-16C asphalt mixture,the elastic-viscoplastic constitutive model based on the load surface is used to characterize the strain softening characteristics of the asphalt mixture.The viscosity coefficient and overstress parameters of the elastic-viscoplastic constitutive model are calibrated by the rate sensitivity test results.At the same time,considering the temperature factor into the constitutive model,the elastic core,the over-stress parameters,the maximum average effective stress history,the rebound index and the variable TEMP shared by the subroutine UMAT and the main program AB AQUS in the constitutive model are correlated,so that the four constitutive model parameters can change synergistically with the continuous variable temperature temperature field of asphalt pavement established by the finite element software ABAQUS,and then the coupling thermal stress analysis of the actual asphalt pavement in the diurnal alternating environment can be simulated.(3)Creep tests with stress levels of 300kPa,400kPa and 500kPa were carried out,and the creep tests were simulated by elastic-viscoplastic constitutive model and ABAQUS.The results show that the simulation curve is basically the same as the test curve,and there is a time-dependent relationship between the rate sensitivity and creep of asphalt mixture.The constitutive model can predict long-term creep deformation through short-term rate sensitivity test.After the unit verification,the model is verified.In this paper,the indoor rutting test is carried out at 35℃,45℃and 60℃,and the rutting deformation of the test is 1.16mm,1.53mm and 3.51mm in the 60th minute.The finite element simulation results are 1.01mm,1.52mm and 3.47mm,respectively.The error between the simulation results and the experimental data is small,which proves the reliability of the constitutive model.(4)The rutting prediction model of asphalt pavement under continuous variable temperature field is established by ABAQUS.Considering the influence of temperature,vehicle speed and axle number,the monitoring data of ring road test of Huning Expressway reconstruction and expansion project are compared.The results show that the variation trends of the rut depth curves of the two are basically the same.The measured rut depth is 19.30mm after 500,000 times of standard axle load,and the finite element simulation results are 19.96mm.The thermal-elastic-viscoplastic constitutive model can effectively predict the rut deformation of asphalt pavement under temperature gradient and different axle load times.