Research On Roughness Characteristics For Pavement

With the development of highway, pavement roughness has been more and more concerned. Smooth pavements not only provide vehicles with a fast, safe, comfortable and economical traveling environment, but also can decrease the destruction of vehicles to pavements, improve the pavement performance and extend the pavement's life. On the contrary, roughness pavements make travel uncomfortable, reduce vehicle velocity, accelerate the damage of vehicle parts and increase vehicle operating cost. Furthermore, pavement roughness induces vehicle vibration which causes dynamic loads on pavement structure. The dynamic loads arise structure responses such as strain and stress which roughen pavements inversely and deteriorate pavement surface.The description methods of pavement roughness are introduced and the important relationship between International Roughness Index (IRI) and pavement power spectral density is deduced firstly. The power spectral density of vehicle dynamic loads is given by solving the motion equations of a quarter vehicle model based on vehicle-road interaction. After defining the dynamic amplification factor, the factor's calculation expression with power spectral density is obtained which can also be expressed with IRI and vehicle velocity based on the relationship between power spectral density and IRI. When IRI is replaced with standard deviation measured by profilometer, another equation can be found. With the riding quality evaluation criterions, the simplified calculation of dynamic amplification factor for asphalt pavements and concrete pavements are both gained. The effect of vehicle dynamic loads upon pavement's service life is analyzed by expressing vehicle dynamic loads on the basis of the simplified calculation of dynamic amplification factor and through the axis loads conversions. And with selecting representative structures of asphalt pavement and concrete pavement, the influence of vehicle dynamic loads on strain and displacement of pavement structures is also analyzed in detail through program computations focusing on the design and checking indices in pavement design specifications. Finally, the two common indices of IRI and Present Serviceability Index (PSI) are used to characterize pavement roughness and performance relatively, and the relationship between the two indices is derived from theoretical analysis by converting both of the two into functions of pavement power spectral density.