Research On Mechanical Characteristics And Optimization Of Adhesive Layer Of Asphalt Pavement Structures On Urban Viaducts

The rapid growth of cities brings intensive flow of people,as well as new oppotunaties for the development of tridimensional traffic like urban viaducts.The flexible pavement structures of asphalt concrete,which are widely used in long-span bridges and urban viaducts pavements,is the major form of present deck pavements.However,pavement diseases of shearing,deformation,cracks etc also appear explosively.Researching and optimizing the deck pavement system and analyzing its mechanical characteristics,which is a matter of great significance,is the premise and foundation of explaining the mechanism and improving pavement performance.The asphalt pavement of one viaduct in Chengdu is taken for example and the actual working condition is simulated in this dissertation.By means of the combination of abaqus FEM simulation and laboratory shear test,relative research on temperature effects,dynamic responses and material structures of waterproof and cohesive layers were done to the bridge deck pavement.The primary work of this dissertation are as follows;(1)Similalities and differences in temperature behaviors between normal road pavement and deck pavement are demonstrated and summarized.Based on typical meteorological conditions in the region of Chengdu,representative real data of both hot and cold seasons were input to thermal analysis module in abaqus to analyze the temperature behavior of deck pavement.The change and distribution laws of temperature field and thermal stress were studied by diurnal variation curves of air temperature.(2)The area nearby the bus station,where the shear diseases are most serious,was set as the research scope,and braking conditions of the new urban transportation system BRT were simulated in abaqus,by using the subroutine written in fortran language.An orthogonal scheme was designed to discuss the sensitivities of each pavement material parameter to different mechanical indexes,which were also taken as the standard to select the most proper pavement structure.As the basic model,the selected system was used to analyze the effects of some factors such as moving speeds of load,values of axle loads,contact state beween layers etc on dynamic responses of the deck pavement,so as to evaluate dynamic characteristiscs of the deck asphalt pavement under different conditions comprehensively.(3)Laboratory shear tests corresponding to the braking force were designed.Taking consideration of the effects of ambient temperature etc on material properties,the oblique shear strength and the oblique shear fatigue properties beween layers of different waterproof and cohesive materials were tested and analyzed.And on this foundation,the combination of materials and structures in waterproof and cohesive layers under variable conditions were evaluated and recommendated.