Research On The Instability Mechanism And Forecast Model Of The Deformation Of The Asphalt Pavement

With the sustainable development of highway and urban road construction in China,asphalt concrete used as the main materials of pavement structure has been widely application,meanwhile,the analysis of the distress and durability of asphalt pavement has become an important research topic to extend the life of the pavement.Rutting is the main failure mode of asphalt pavement in the semi-rigid base,which seriously affects the comfort and safety of driving.There have been a lot of researches on the development of rutting depth,however,there is less research on the analysis and prediction of rutted time points.This paper mainly utilize the triaxial shear strength test,triaxial dynamic creep test and penetration dynamic creep test,combined with the finite element analysis,to obtain the creep instability prediction model of the laboratory specimen,and come up with the prediction method for rutting and instability of asphalt pavement.This study is of great practical value for the determination of maintenance time points in practical road maintenance projects.First,the triaxial shear strength test was used,and the shear strength parameters of asphalt mixture,namely cohesion c and internal friction angle?were obtained.Moreover,the effects of different temperature on c and?were investigated,and the prediction model of the shear strength parameters with temperature correlation only was established under a certain gradation.Furthermore,the influence of additives on the shear strength parameters were also considered,the testing results show that the parameters c and?are all improved after adding a certain amount of additives.By simplifying the calculation method of the shear stress value?in the failure plane under cyclic loadings,the prediction model of the value?is presented.Secondly,the rheological times F_N corresponding to the instability point of asphalt mixture was obtained by the triaxial dynamic creep test,and its rationality was analyzed.Moreover,considering the influence factor such as confining pressure,cyclic pressure value and mixture gradation and other factors,the instability prediction models of AC13 and AC20gradation mixtures were established by the exponential model fitting analysis under a test temperature 60?,and the rationality of the model was aslo verified.Furthermore,the variation of parameters in the model was studied by changing the test temperature,and the prediction model of instability points of AC13 and AC20 mixtures in the whole temperature range were established by interpolation,and it was also validated.Then,the penetration dynamic creep test based on the change temperature field was realized by applying the coating material,the internal stress and temperature field of the specimen were obtained by combining with the ABAQUS finite element analysis.The model was established and analyzed with a sublayer of 1cm thick,and the temperature field and the stress state are equivalent to the instability prediction model in each layer.If more than 50%of the sublayer instability occur,it can be considered as the overall instability of the material,so the prediction model of the penetration dynamic creep instability is established.Using prediction analysis and test verification of the single layer and multilayer asphalt mixture,the results show that the estimation model is reliable.Furthermore,the effects of anti-rutting agent,temperature,loading change and longitudinal slope on the instability of the mixture were analyzed,the research shows that the addition of anti-rutting agent and the overall decrease of the internal temperature field can prolong the life,but it obviously shortens the life of materials with the increase of loads and slope.Finally,the finite element model of asphalt pavement was established using ABAQUS analysis,and the method of rutting prediction was put forward to points out the statistics for the actual pavement prediction,such as environmental temperature change,traffic volume,and so on.Moreover,the simplified substitution method for the statistical data is proposed,and an example is given to estimate the rutting of asphalt pavement.Based on the above research,the prediction model proposed in the paper can realize the prediction of the laboratory asphalt mixture specimens according to actual temperature field and the time of instability in the field asphalt pavement,It provides an effective basis for the determination of curing time in the actual road and the control of the rutting in the asphalt pavement.