Study On Mechanical Properties Of Asphalt Overlay On Old Cement Concrete Pavement

With the development of urbanization construction of China, and the rapid construction of urban roads, lots of cement concrete pavemens were constructed, which accelerated the economic and social development. However, the cement concrete pavement built earlily has being almostly reached or met the design service life, reached the overhaul and medium repairmen of pavement, which appeared different kinds of structural damage and functional defects. At present, the technology of asphalt overlay on old cement concrete pavement, as the main methods of the old cement concrete pavement overhaul and medium repair, is focused on the influence factors of structure inner stress and stress, and the methods to control them. Because of the old cement road surface crack, and more other factors that effects of the characteristics of interlayer mechanics, the asphalt layer between old cement road surface and the stress characteristics and various influencing factors of the study of the relationship analysis is relatively complicated, and not studied in detail.With the analysis finite element software ABAQUS, three dimensional finite element model, the asphalt overlaying on old cement concrete pavement structure, has been established, through which the effects of thickness of asphalt overlay, overlay modulus, fracture, overload, interlayer thickness, sandwich modulus on asphalt overlay bottom layer of maximum principalstress and vertical direction of maximum shear stress has been studied. It is also obvious that increasing the thickness of asphalt overlay can reduce the maximum principalstress and vertical direction of maximum shear stress on the bottom of asphalt overlayer. Increasing the modulus of asphalt overlayer can’t reduce the maximum principalstress and vertical direction of maximum shear stress on the bottom of asphalt overlay. The maximum principalstress and vertical direction of maximum shear stress on sphalt overlay bottom layer increase with the increasing of load straightly. The influence of fracture effect the maximum principalstress on sphalt overlay bottom layer is smaller(1%-2%), while greater impact on the vertical direction of maximum shear stress on sphalt overlay bottom layer. Increasing interlayer thickness can’t significantly reduce the maximum principalstress on sphalt overlay bottom layer, and increase the vertical direction of maximum shear stress on sphalt overlay bottom layer. The maximum principalstress on asphalt overlay bottom layer shows a trend of increase with the increasing of sandwich modulus, and the vertical direction of maximum shear stress on sphalt overlay bottom layer shows a trend of decrease with the increase of sandwich modulus. In addition, through laboratory-scale experiments to verify the availability of software simulations, and found fracture, eccentric load, overload will noticeably increase asphalt layer of stress on sphalt overlay bottom layer, promote the destruction of road structure, and pave asphalt layer can make the damage slow effectively.This dissertation also simulate the temperature field of the structure of asphalt overlay on old cement concrete pavement. Based on the analysis of different road surface temperature of pavement structure, found that the temperature inside the road structure influence by road surface temperature, heat conduction parameter, pavement structure specific heat capacity and thermal conductivity coefficient. Under different temperatures, different road structure material make its produce large temperature stress in each layer of contact surface, especially produce the large temperature stress between the new add asphalt surface layer and the old cement surface layer; With the increase of asphalt surface temperature, the temperature stress between the new add asphalt surface layer and the old cement surface layer increases.