Mechanical Behavior Of Continuously Reinforced Concrete Rigid-flexible Composite Pavement Under Thermal And Mechanical Coupling

Continuous reinforced concrete rigid flexible composite asphalt pavement(CRC+AC composite pavement),which has the following advantages such as high strength of the overall structure,longer service life,more comfortable driving,lower cost in maintenance,etc.,is an important long-life pavement structure for heavy-loaded traffic in China.The durability of asphalt layer directly affects the road usage performance and service life of pavement structure.The research on the mechanical behavior of asphalt pavement under the coupling action of temperature and three-dimensional non-uniform load has theoretical significance and practical value for revealing the cracking mechanism of asphalt pavement and controlling the early failure of asphalt pavement.Based on the multidisciplinary theories such as ABAQUS finite element software,heat transfer,mechanics,material science and so on,the thesisstudies the mechanical behavior of CRC+AC composite asphalt pavement under temperature and three-dimensional non-uniform load through simulation analysis.Firstly,by establishing the CRC+AC composite pavement temperature field model and collecting the data from the temperature sensor of Beij ing fullscale ring road test road,the thesis verifies the reliability of the temperature field simulation model,and analyzes the variation law of temperature field and temperature stress under the condition of continuous temperature change.Secondly,the thesis also simulates and analyzes the influence of AC layer modulus,AC layer thickNess,CRC layer modulus,CRC layer thickNess and cooling on the temperature stress of structural layer.Thirdly,the thermal mechanical coupling simulation model of CRC+AC composite pavement is established,and through using the FWD deflection basin data measured in a real project at a certain temperature,the thesis could verify the reliability of the thermal mechanical coupling simulation model of CRC+AC composite pavement.Considering the coupling effect of temperature and three-dimensional non-uniform load,with the tensile stress and shear stress at the bottom of AC layer at the crack of CRC layer as the index,the thesis determines the unfavorable season which is around 6:00 in the morning in winter and the unfavorable load position which is located directly above the edge of the transverse microcrack(grain)in the CRC layer at the rear edge of the tire.the mechanical response law of the loading area on the surface and bottom of AC layer is determined under three kinds of unfavorable conditions including vehicle turning,emergency braking and emergency braking at turning.Based on the mechanical analysis under unfavorable load position and the observation results of solid engineering,the thesis reveals the inducement,expansion mechanism of surface and bottom cracking of asphalt layer.The influence of AC layer thickNess,AC layer modulus,vehicle axle load,driving speed and the size of microcrack(grain)in CRC layer on the mechanical response of AC layer is studied.Four factors and four levels orthogonal test was designed for sensitivity analysis,and the test research shows that the thickNess of asphalt layer and vehicle axle load have the greatest influence on the mechanical response of asphalt layer.Therefore,considering the analysis results of influencing factors of mechanical response of asphalt layer and engineering economy,the most suitable thickNess of asphalt layer should to be 8～12cm.In summary,the research results can provide reference value and researching basis for the improvement and development of design theory of continuous reinforced concrete rigid flexible composite pavement.