Interfacial Performance Of Pavement Based On Fracture Mechanics Theory

The existing design theory for pavement structure is based on multi-layer system, which treats the road as a construction composed of several elastic layer with completely continuous or no friction interfacial boundary. There is little research about the state for pavement with discontinuous interface. Once the continuity of interface is damage, the transfer mode for the whole structure will be broken. Then the stress condition of road will become very terrible especially the surface layer. The discontinuous interfacial boundary becomes one of direct cause to destroy the pavement. Interfacial fracture mechanics and viscoelastic theory are applied to research the interfacial performance of pavement structure, mean while experiments are used to verify the results of theoretical analysis and explore the ways to enhance the interfacial performance of pavement. This paper mainly discusses the problems from the following several aspects as show:Interfacial fracture mechanics of composite material is applied to road analysis. The soil base is simplified as the Winkler foundation. The pavement with an interfacial crack which is between surface and base layer becomes a laminated structure on Winkler foundation. The horizontal constraint between the soil foundation and base is divided into freedom and fixed. In order to obtain the solution of the equation, Fourier integral transform is used to simplify the ordinary differential equation. With the help of dislocation density function, residue theorem and numerical method for singular integral equation which is called chebyshev polynomial, the stress and displacement expression for any point of the road with interfacial crack are deduced; the crack tip stress intensity factor is also calculated by means of numerical solution. By analyzing the interfacial crack tip stress intensity factor which changes with different material parameters of layer, a reasonable combination of pavement structure with discontinuous interface is obtainedThe surface layer of pavement is viscoelastic media, in this discussion it is recognized as a linear viscoelastic material. Combining with the corresponding relationship between linear viscoelastic medium and elastic material in Laplace space, the stress and displacement expression for any point of the road with interfacial crack in Laplace space are deduced; the crack tip stress intensity factor in Laplace space is also calculated. With the help of the inverse Laplace transformation, the stress and displacement expression for any point of the viscoelastic road with interfacial crack are deduced; the crack tip stress intensity factor which changes over time is also calculated by means of numerical solution. By analyzing the interfacial crack tip stress intensity factor which changes with different viscoelastic material parameters of surface layer, the combination of surface and base layer is established which is basic on modulus annenuation.Through the rutting test, low-temperature splitting test and immersion Marshall Test, high temperature stability, low temperature crack resistance and water stability performance are compared to make sure the applicability of fiber reinforced asphalt mixture and ordinary one for pavement interfacial test.The interfacial performance of actual pavement core specimen is considered as while as to verify the shear device and the molding method. With Bonifibers, the discussion focuses on the influence of the layer material on the pavement interfacial performance. The laboratory specimen is planed for interlaminar shear fatigue test. Through interlaminar shear fatigue test under different frequency, an interlaminar shear strength coefficient considering the effect of vehicle velocity is set up.