Study On Damage Behavior And Structural Life Reasonable Matching Of Long-life Asphalt Pavement

The essence of long life asphalt pavement is that the pavement would not occur structural destroy during the design service life of a pavement. The upper layer of the pavement is the only part that would damage, so pavement maintenance will be more effective as it only need to renew the destroyed upper layer of the pavement without structural repaired treatment. The theory of long life asphalt pavement should depend on the optimization of asphalt pavement structure, layers location and thickness to extend the life of asphalt pavement and reduce the maintenance cost. In recent years, the asphalt pavements of our country face with the challenge of the increasing pavement loading, especially the heavy loading traffic. Basic on traditional design system of pavement structure, the pavement would be destroyed before the design service period and need major repair. It leads to traffic jam and increases the traffic pressure of the highway and urban arterial road. In order to enhance the total quality of the highway asphalt pavement, reduce the pavement maintenance, upgrade the pavement service, cut down the consumption of material, save the energy, increase the economy and society efficiency and make contribution to the asphalt pavement structure design theory. This paper, basic on the analysis of asphalt pavement structure of our country, research on the parameter indexes and forms of damage and failure which effect the life of long life asphalt pavement, the structure response and the damage behavior of long life asphalt pavement by applying FEM, damage evolvement of asphalt mixture by multiscale modeling method from material science point of view. Combining with the idea of long life asphalt pavement at home and abroad, it raises the asphalt pavement life matching theory, optimize the asphalt pavement structure of our country by this theory and make it meets the requirement of long life asphalt pavement.Base on types of asphalt pavement and destruction forms, indexes and parameters which infused the deterioration of asphalt pavement were analyzed. According to the result, several forms of long life asphalt pavement destructions were put forward. A suitable model for dynamic modulus prediction was proposed to determine the design parameters of long life asphalt pavement; this model was base on the comparison and analysis among several advanced prediction models and on the verification of prediction model using test data from a dynamic modulus experiment of asphalt mixtures. The asphalt pavement fatigue prediction model was validated by comparing. The fatigue limit of asphalt pavement was determined based on the elastic-viscoelastic theory of asphalt mixture.In traditional pavement design, base on the theory of elastic layered system the calculated results were different from an actual pavement in condition of elastic layered static load, in the shape of action area, in the load distribution and in the assuming of material characteristic. The stress-strain behavior of different types of asphalt pavement were analyzed and the damage mechanism of long life asphalt pavement was analyzed at the same time, using transient loaded implicit-dynamic FEM and the pavement response of dynamic load in different load states, different temperatures and different speeds were considered. The result indicated that thick layer asphalt pavement possessed better damage tolerant, whose rutting depth was less than thin layer asphalt pavement. To some extent, with the increasing of pavement thickness, the thickness of pavement could play less important role in the properties of rutting. Top-down crack was not generated in the surface of a pavement but in the shallow layer of a pavement structure, and the most favor states for Top-down crack was when the mixture possessed weak bonding and in high temperature. According to the result, a mixture that was sensitive to rutting also sensitive to cracking. But it was not possible for Top-down crack be generated at low temperature, or event none. The assuming that the tire-pavement contact stress was uniform distribution could lead to a result that underestimated the damage of pavement in shallow layer, especially in high temperature.The theory of multi-scale simulate method of micromechanics was applied to analyze the damage behavior of asphalt mixture, which could help comprehending the cause of Top-down crack that was the main damage form of the long life asphalt pavement. In the last part of the study, the typical asphalt pavement structure in China was optimization analyzed basing on the idea of matching of structure life. It was considered that asphalt pavement on semi-rigid base could fulfilled the requirements of long life pavement by reasonable matching the service lives of each layer by optimizing materials and thickness.The major results obtained in the research would lay a solid theoretical foundation for asphalt pavement design, improve the overall quality of asphalt pavement and extend its life.