Research On Prediction And Influence Factors Of Pavement Friction Coefficient Based On DFT Simulation

To detect the skid resistance of pavement,many field pavement testing equipments are developed.However,the obtained pavement skid resistance indicators can only reflect the contact between rubber and pavement under specific test conditions.Many scholars argue whether those indicators are reliable enough to represent the real tire-pavement contact and reasonable to evaluate of skid resistance.With the development of digital technology in pavement texture reconstruction and finite element method(FEM)for tire pavement contact behavior,researchers gradually explore the use of numerical calculation to measure the skid resistance of pavement.Therefore,this study hopes to virtualize procedures of pavement friction coefficient measurement.To this object,the point cloud data of field pavement texture scanned by threedimensional laser is used to construct digital pavements for FEM models.Then,the procedures of dynamic friction test is simulated by the FEM as well to predict the friction coefficient.Detail works include:(1)Pavement texture digitization: The point cloud data of pavement texture is obtained by3 D laser scanning.The 3D surface and solid model of pavement profile are reconstructed in Geomagic studio and UG NX 12.0 respectively,which are finally imported into ABAQUS to establish the 3D finite element model of pavement texture.(2)Dynamic friction test(DFT)of three typical pavements: SMA-13,Fine Friction Course?,and UT-5 are selected in a experimental road section of a expressway of Xinjiang Uygur autonomous,PRC.DFT is used for field measurement to obtain the friction coefficients.(3)Construction and validity of friction coefficient prediction model: combined with(1)the three-dimensional model of pavement texture,the contact analysis of rubber-water-flow pavement three-phase coupling is carried out,and the FEM for friction coefficient prediction is built.The prediction values of friction coefficients for three pavements and verified by the field mesurement data;(4)Analysis of influence factors of friction coefficient: effect of pavement dry/wet state,water film thickness and texture characteristics on friction coefficient are evaluated based on the prediction model.The results show that the p-value between the predicted and measured values(n = 6)of the friction coefficient for SMA-13,Fine Friction Course?,and UT-5 under different speed is greater than 0.05,so it is considered that there is a significant correlation between them.The critical water sliding velocity((8,the rubber is completely separated from the pavement)of rubber block under different water film thickness is evaluated,for example,(8 of SMA-13 is 60km/h,and (8 of Fine Friction Course? and UT-5 is 85km/h when the water film thickness is 1.5mm.According to the thickness of water film,the contact between rubber and wet pavement can be divided into three states: boundary lubrication,mixed lubrication and fluid lubrication.Therefore,the friction coefficient prediction model constructed in this study realizes the prediction of rubber pavement friction coefficient under limited conditions.