Based On Dynamic Modulus Of Flat Crossing Of Asphalt Pavement Rutting Prediction Model Research

In recent years,with the constant improvement of the level of urbanization,the development of road traffic,increasing of traffic and the overload phenomenon combined with the climate warming,the phenomenon of asphalt roadbed disease is more and more serious,especially the flat at the junction.Due to the traffic control,when a vehicle is starting or braking,a great horizontal force is produced,which aggravate the disease.However,the research of asphalt pavement rutting prediction model mostly focus on the general road,less on the estimate of the crossing.Based on the above reasons,this paper firstly investigates the disease forms of the flat crossing section of asphalt pavement,analyzing its reason and considering that crossing jostled,hug and rutting of asphalt pavement disease compared with general sections are affected by many fatal factors.However,the larger horizontal force when vehicle brake or starts,the waiting for light in scorching weather,and the channelized traffic are the most fundamental reasons.When the pavement structure under vehicle load,its actual working stress in a dynamic system,therefore,it is necessary to study the dynamic parameters of asphalt pavement materials and rut forecast dynamic parameters.The paper use proportioning design on the selected gradation of asphalt mixture.Using rotating compaction meter molding specimens and SPT test instrument for dynamic modulus test,analyzing the change rule of dynamic modulus,phase angle and dynamic modulus index under the coupled action of frequency and temperature,and using the basic ideas of Sigmoidal function and dynamic modulus of Witczak model,the dynamic modulus of forecast model considering temperature,frequency,oil-stone ratio,void fraction and mixture gradation characteristics is put forward.Extracting the phase Angle change with load frequency curve under different temperature,through the analysis of regular,according to the T ≤25 ℃、 25 ℃ < T < 30 ℃、T ≥ 30 ℃ three temperature period of processing,test results is disposed.Firstly,control variable method is used to analyze the correlation of each factor and the phase Angle and determine the introduction form of every parameter.Then using wheat Marquardt method(Levenberg-Marquardt)+ general global optimization algorithm on experimental data,phase Angle forecast model including factors such as temperature,frequency,oil-stone ratio,void fraction,and gradation characteristics is proposed.Base on the equivalence principle,using the nonlinear least squares regression fitting shift factor under different temperature,determining the WLF equation coefficient of temperature dependence of the asphalt mixture viscoelasticity and Prony series parameters of time dependence,and using ABAQUS software to establish three-dimensional finite element model of viscoelastic analysis of asphalt pavement,horizontal force and braking force is applied to simulate asphalt roadbed stress under different horizontal force situation.By analyzing the viscoelastic mechanics response of asphalt layer,the results show that the different horizontal force caused by the change of stress and strain state of asphalt pavement are not allow to ignore and it is the important reasons of flat crossing hug,push,rutting of asphalt pavement diseases.Analyzing the influence factors of rutting,determining to select the parameters in the rut forecast model,simulating different thickness and different temperature rutting test,compared with indoor rutting test results,verifying the accuracy of the finite element model and viscoelastic parameters,extracting different coefficient of horizontal force in pavement structure and the shear stress values of layer,and using analysis of regression on the date,the rut forecast model based on the indoor test flat crossing is established.According to the actual road environment conditions,revising the load forecast model to serve the actual road better.