The Research Of Temperature Influence On Asphalt Concrete Fatigue Propagation

In recent years, with the extensive development of transportation infrastructure construction in our country, construction of expressways is more frequent in the central and western regions of our country. The geology condition in these areas is very complex, at the same time, the design specifications for expressways set higher standards for design and construction. This makes construction of expressways inevitably encounter many difficulties such as half-filled and half-dug sub grade, high-fill sub grade and large longitudinal slope. In general, the domestic design theory about the special topography and geological conditions is still in its infancy, this will seriously restricts the construction quality and long-term service performance of the expressways in the central and western regions of our country.Moisture is the most important environmental factors that affect sub grade resilient modulus of asphalt pavement. Based on the current research results, the sub grade moisture conditions and relative factors, the methods to characterize sub grade moisture, and the modified coefficients of resilient modulus are summed up in the dissertation.Firstly, the influence on pavement structure induced by insufficient compaction on the edge of sub grade is studied with ABAQUS software. Based on the relationship between compactness and physical parameters of the sub grade soil, the settlement and additional stress in sub grade and pavement structure induced by insufficient compaction of road shoulder are analyzed in different compactness and different traffic loads. The mechanism of pavement failure is proposed, and some efficient construction and maintenance measures are put forward based on the failure mechanism.Secondly, for large longitudinal slope which filling height changes, a three-dimensional finite element model is set up to simulate its consolidation settlement. According to the calculation results, the influence on foundation, subgrade and pavement structure induced by varied filling height are studied. The linear relationships between differential settlement of foundation, settlement of pavement, displacement at toe of slope and filling height are discovered. The importance of layered filling is emphasized according to the additional stress condition on the bottom of sub grade.Finally, ABAQUS finite element model is established to study the influence on semi-rigid base and flexible base asphalt caused by differential settlement of half-fill and half-dug sub grade. Mechanical response is analyzed in asphalt pavement by applying displacement load on the top of sub grade, studies the law that differential settlement influence on additional stress in pavement structure. According the study result, some suggestions are given to the expressway construction in mountainous areas.