| The study on the asphalt pavement mechanics behavior in service and the asphalt overlay's crack propagation is a popular and advanced topic in the asphalt pavement researches. The exploring on the mechanics behavior and crake expanding performance of asphalt pavement will contribute to a better understand on working state of the asphalt pavement, which is the base for further discovery on the causes of the immature damage, and can guide the asphalt pavement design and rehabilitation. The thesis makes the numerical and test study on the asphalt pavement's mechanics behavior and the crack propagation. The main works in the thesis are as following:(1)Based on the visco-elasticity of the asphalt concrete, the thermal stress responses of the pavement are studied considering the contact mechanics of the interface by the finite element method. Further, the influence of the initial temperature, the cooling range, the cooling rate, the overlay's thickness and the base module on the temperature stress response is analyzed.(2)The dynamic response of the asphalt pavement under the moving wheel loads is analyzed using the finite element method. The non-reflective boundary is introduced to avoid the disturbance for the limit size of the finite element model's domain which would reflect the wave at the model's boundary, and the visco-elasticity of the asphalt concrete is taken into account too. The influence of the base module, the base's thickness, the contact condition of the interface, the damping, the velocity of the wheel loads is studied.(3)The coupling method combining the element free Galerkin method (EFGM) and the finite element method (FEM) is discussed. The usual coupling methods are addressed, while two widely used methods-interface elements approach and collocation approach-are presented in detail on its theory bases and the linear consistency. A simplified transition element method is represent based on traditional transition element method, which is proved valid by the numerical sample.(4)The application of EFGM on the crack propagation is addressed. Two methods-contour integral and area integral- are introduced to calculate the stress intensity factor (SIF) of the crack tip, and their implements are explained. And the crack propagation modeling attracts much attention, especially on the crack criterion, the selection of the crack increment, the refreshment of the geometry. Some samples on the crack propagation simulation work have been offered. The application of EFGM in the field of Crack Mechanics and Crack Propagation is proved to be available by numerical case studies.(5)The fatigue characteristic, fatigue life and crack propagation path of the pre-sawed asphalt concrete beam have been studied by the three-point bending fatigue test. Furthermore, the test has been numerical simulated with the program based on the coupling of EFGM and FEM. The result of the test and simulation shows that, the fatigue life ascends with the increase of the distance between the loading point and the sawed crack. And the fatigue life descends with the increase of the stress level. The crack propagation path abides certain rule in general. And the test demonstrates that the path propagates along the boundary of the aggregate nearly not splits the particles.(6)The crack propagation path of asphalt pavement under wheel loads is firstly simulated by the coupling of EFGM and FEM method interiorly. The influences of the overlay thickness, the base modules, the overloads, the loading positions are evaluated in detail by parameter analysis. The loading position and the module of overlay and base heavily influence the crack propagation path. The SIFs are calculated along with the crack propagating. The crack angles are also analyzed, and the results show that the crack angle will change with the crack propagating. The various combinations of depth and rigidity will make different crack propagation behavior of asphalt pavement.
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