Dynamic Response Analysis Of Pavement Structures Considering Contact Characteristics

Structures with a gap are very common in pavement engineering,such as the cases of crack repairing and pavement widening.The main purpose of this article is to analyze dynamic mechanical response of such structures,with consideration of the geometry contact and interface bond characteristics between two materials on two sides of the structure.Cracking is a common distress in cement concrete structures,the study about the morphology and reconstruction of fracture surfaces is beneficial to quantitatively evaluate the repair efficiency.After obtaining the fractal dimension D and the fractal roughness G of a real fracture surface basing on a self-made profile instrument,a three-dimensional geometrical model of a crack region could be reconstructed through the combination of two two-dimensional Weierstrass-Mandelbrot fractal interpolation functions.Effectiveness of the method of reconstructing the crack region was verified by an impact test of a specimen containing a crack.Full-scale simulations of the concrete pavement model including reconstructed crack regions and moving vehicle tires were implemented,and the results showed that mechanical states of the crack region using irregular fracture surfaces were worse than those using regular fracture surfaces.Hydration kinetic of cement-based material is used as an example to analyze strength formation process of crack repairing materials.An iterative algorithm used to determine accurate hydration kinetic parameters was put forward.Hydration rate curve,which was created by kinetic parameters,coincides with experimental data.The numerical model of cement hydration can predict temperature variation of cement concrete under adiabatic condition and replace the standard adiabatic calorimeter test.The exponential function of cement hydration,which was obtained by area ratios of hydration products in BSE image recognitions,fits well with experimental data and can be used to analyze hydration kinetics instead of conventional hydration heat method.In conclusion,the research work in this article could improve the accuracy of hydration kinetic parameters and provide new research means for hydration kinetics analysis.Finally relationship between dynamic of elastic modulus of cement stabilized macadam and hydration degree(or time)were studied,as preparations to select reasonable curing time of base layer in pavement widening.As for pavement widening,the best stage sizes of surface and base layer were respectively obtained,basing on the strain energy density index calculated by numerical models two-dimensional pavement widening.A three-dimensional pavement widening model was built and coupled with tire model used such combination of stage sizes.Strain energy density of the points,which lied in the bottom of asphalt concrete layer and cement stabilized macadam and above the split joint,were analyzed using the 3-D model.Different material parameters of interface and cement stabilized macadam,also different thicknesses CA mortar layer were all analyzed.Relationship between strain energy density under single loading and fatigue lives of small beam under bending test was formulated,using numerical model of bending test.The fatigue lives of asphalt concrete layer and cement stabilized macadam layer were then derived through calculation results of 3-D pavement widening model.