Mechanics Analysis Of Asphalt Concrete Overlay On The Old Cement Concrete Pavement At Steep Slopes And Sharp Turns

At present, many domestic and foreign cement concrete pavement built before has undergone various diseases, which seriously impact on pavement performance and may no longer meet the traffic demand. It is one of the main measures to rehabilitate old cement concrete pavements with paving asphalt overlays. It can not only improve the level of performance, but also can increase bearing capacity and extend the service life.As joints and cracks exist in old cement concrete pavement, they will expand and extend to the asphalt overlay under the action of traffic load, environmental factors and interaction of other factors and finally lead to reflective cracks. The result is that it will destroy the integrity of the pavement structure and easily form early destruction. Especially at steep slopes and sharp turns in a road, the pavement suffered more complex load and larger internal forces in overlay, so reflective cracks, ruts, the passage and other diseases occurs easier in the overlay. As one of the important measures to prevent reflective cracking of asphalt overlay, the stress absorbing layer has more advantages, which typically has lower elastic modulus and high toughness, and absorbs stress on concrete slab joints through its strong ability of plastic deformation, thereby effectively reduce the generation and spread of reflective cracks. Therefore, it's necessary to analyze the stress state of asphalt overlay over old cement concrete pavement at steep slopes and sharp turns and to research the impact that stress-absorbing layer have on load stress of asphalt overlay. Based on previous studies, the paper continues to further research these two issues by theoretical analysis.By using three-dimensional finite element method and ANSYS finite element program, the article establishes a three-dimensional finite element model of pavement structure of asphalt overlay on old cement concrete pavement. And by using the material strength theory, the paper analyzes the internal force of asphalt overlay structure at steep slopes and sharp turns, and researches the effect that stress-absorbing layer have on the stress of asphalt overlay. The main contents are as follows:(1) The response that tensile stress, shear stress and deflection difference act at the surface and the bottom of asphalt overlay under different longitudinal horizontal load is analyzed.(2) The feature that how the maximum principal stress, equivalent stress, the maximum shear stress and the maximum tensile strain have at different depth under longitudinal and transverse horizontal load is explored.(3) The influence that different asphalt overlay thickness, modulus and axle load have on internal force and deflection in asphalt overlay is analyzed under a certain level of horizontal load.(4) The influence that different thickness and modulus of stress-absorbing layer have on load stress and deflection of asphalt overlay and stress-absorbing layer itself is studied, and reasonable thickness and modulus of stress-absorbing layer is explored.