Theoretical Analysis Of Pavement Structure With Cracks

In recent years, with the development of highway transportation, the construction of main road network has been finished in our country. Therefore, more and more engineers and experts pay their attention to the research of pavement maintenance and rehabilitation. Cracking is one of the main forms of early damage of pavement structure caused by cyclic traffic and temperature loads. With the propagation of cracks in the pavement, it will seriously affect the travelling safety and comfort. In order to evaluate the comprehensive situation of the pavement and take the appropriate measures to repair the road, the research for the pavement with cracks and pavement with an overlay is necessary. This dissertation has mainly covered the studies on four issues as follows:(1) In order to simplify the problem, a cement concrete pavement is reduced to an elastic plate on Winkler foundation with cracks on the surface or at the bottom. To solve the problem simply, the Fourier transform is used to convert the partial differential equations into the ordinary differential equations. Dislocation density function is introduced and the residue theorem is used to calculate the complex integrals. Lobatto—Chebyshev integration formula, as a numerical method, is used to solve the singular integral equations. The numerical solutions of stress intensity factors at the crack tip are given. Cement concrete pavement with a crack is considered with the method described in this part and the influence factors are analyzed that affect the stress distributions near the crack tip. According to the results of calculation, appropriate decisions on whether the old road should be repaired or not can be made.(2) A model for asphalt concrete pavement is established. It is reduced to the elastic multilayered structure with a crack in one layer perpendicular to the surface. To solve the problem simply, the Fourier transform is used to convert the partial differential equations into the ordinary differential equations. Dislocation density function is introduced. According to the boundary conditions, the residue theorem is used to calculate the complex integrals and the stresses and strains of any point in the pavement can be expressed by the dislocation density function. Lobatto—Chebyshev integration formula, as a numerical method, is used to solve the singular integral equations. The numerical solutions of stress intensity factors at the crack tip are given. The stress and strain distributions near the crack tip are analyzed by the method mentioned in this part. (3) To analyze the mechanical behaviors of the cement concrete pavement with an asphalt overlay, the expressions of stresses and displacements are derived and the numerical results of the stress intensity factors of the crack tip are calculated. Comparing the numerical results of stress intensity factors with different thicknesses and elastic moduli of the overlay and different horizontal distances of the traffic load from the crack, the main factors that impact the overlay and optimize the technology of asphalt overlay are obtained.(4) In order to analyze the mechanical behaviors of the asphalt concrete pavement with an asphalt overlay, the expressions of stresses and displacements are derived and the numerical results of the stress intensity factors of the crack tip are calculated. The actions of asphalt overlay which resist the growth of cracks are analyzed and the stress intensity factors of crack tips with different elastic moduli of the asphalt overlay and different horizontal distances of the traffic load from the crack are obtained and compared.