Research On Evaluation Indexes Of Mechanical Performance Of Flexible Pavement Based On Full-scale Rutting Test

Rutting is the permanent deformation of asphalt pavement caused by the combination of traffic load and environmental factors.This deformation will affect the passenger’s comfort experience and shorten the service life of the pavement structure.Therefore,scientific and rational evaluation of road surface rutting can prevent aviation accidents caused by the rutting,and provide a basis for decision-making for road surface maintenance.The study indicated that the translational shift of load position of aircraft can be well reproduced in the CC5 test carried out by NAPTF,so a serieos of turning points appeared in the rutting curves.The rutting depth and horizontal coordinate of such turning points were extracted and processed.The standard deviation S is obtained by fitting the function of the normal distribution on the rutting profile according to the wheel load in the test.The multi-dimensional rutting profile evaluation index is proposed:1)Characteristic points of rutting section RD_i;2)The average value between each feature point????;3)Standard deviation S between each characteristic point rutting;4)Rutting area A;5)Aspect ratio(2?₀;The average rutting depth????represents the overall level of pavement surface deformation,and the standard deviation S value represents the degree of dispersion of the feature point rutting depth.The introduction of the rutting depression area solves the effect of different rutting shapes on the pavement structure with the same rutting depth.By the CC5 test data the Multidimensional Evaluation index of the rutting are verified.This paper uses ABAQUS finite element software to perform simulation tests and expand the working conditions.The equivalent loading method of moving loads and the cyclic loading process are improved to simplify the finite element model.Firstly,a three-dimensional asphalt pavement model is established,based on the deformation equivalent principle,the mobile load is equivalent to a semi-sinusoidal carrier that changes uniformly with time.The influence range of the load in the length-width direction and the depth-dependent Winkler foundation model are considered,which improves the calculation efficiency of the model.CC5 test was used to verify the accuracy of the model.Combining the effect of time interval on the rebound of asphalt material during the application of two adjacent loads on the actual airport pavement,it is concluded that when the time interval is 150s,the rebound of asphalt material tends to be stable;Using previous research and analysis of the CC5 test data,it is concluded that the initial rutting has an important impact on the long-term development of the rutting.According to previous research the CC5 test study found that when the loading times were 10%before the loading times,the rutting development had reached 40.44%of the final deformation.The development of the initial rutting is used to estimate the prediction formula of the flexible pavement under different temperature and stress conditions,which simplifies the calculation cost.