Study on Crack Propagation Behavior of Composite Base Asphalt Pavement Under Dynamic Load
Based on the theory of fracture mechanics and finite element numerical simulation method,a three-dimensional model of the composite base asphalt pavement with a crack on Senegal MBOUR-KAOLACK(MK)expressway was established.The influence of the load and pavement structure layer parameters on the stress intensity factor of the composite base asphalt pavement at the initial stage of crack propagation was analyzed.The variation law of stress intensity factor when the crack expands upward was analyzed,and compared with the semi-rigid base pavement with equal thickness.The results showed that the extreme value of the stress intensity factor increased gradually with the decrease of vehicle speed or the increase of axle load,leading to the risk of pavement crack propagation increases.The higher the pavement structure layer thickness and asphalt layer modulus,the lower the stress intensity factor.Among them,increasing the thickness of the semi-rigid subbase and increasing the thickness of the surface layer had similar reductions in the stress intensity factor,so increasing the thickness of the semi-rigid subbase was more economical.However,the increase of the modulus of the subbase would lead to the increase of the stress intensity factor,and the use of a high modulus subbase should also be avoided.As the cracks expand upward,the K,of the composite base asphalt pavement and the semi-rigid pavement first increased and then decreased.The KⅡ gradually increased,and the dominant mode of cracking gradually changed from the tensile mode to the shear mode.In the process of crack propagation upward,the KⅠ decline range of the composite base asphalt pavement was greater than that of the semi-rigid base pavement,and its stress intensity factor was also smaller than that of semi-rigid base asphalt pavement.It could be seen that the crack resistance of the composite base asphalt pavement was better.
万方数据
