沥青路面表面纵向与横向疲劳裂缝扩展研究

基于自上而下的表面纵、横向疲劳裂缝严重影响沥青路面的使用品质,首先分析表面疲劳裂缝的形成机理,然后采用奇异等参元法及断裂力学理论,应用有限元软件ABAQUS,建立20结点等参立方体单元的有限元模型,数值计算路面表面纵、横向疲劳裂缝扩展,探讨表面纵、横向裂缝疲劳扩展的规律。计算表明:①表面纵、横向裂缝扩展只考虑偏载作用,随着裂缝向下扩展,其K2是增大到一个峰值后,再由此下降。裂缝扩展前期,纵、横向裂缝的K2差别不大,而在中后期,纵向裂缝的K2要大于横向裂缝。②各路面结构参数中面层厚度h1和模量E1及基层模量E2对表面纵、横向裂缝扩展影响较大,其它参数(土基模量E0、底基层厚度h3和模量E3、基层厚度h2)则影响很小。

Research on Fatigue Cracks Extend in Transverse and Longitudinal Direction of the Asphalt Pavement Surface

The top-down fatigue cracks on the surface seriously affect the using quality of asphalt pavement.Formation mechanism of surface fatigue cracks was analyzed.Then,based on singular and other parameters together with fracture mechanics theory,a finite element analysis model of 20-node isoparametric elements was established by the FEM software ABAQUS.The surface cracks in transverse and longitudinal direction were numerically analyzed,and the extend rules were studied.Results indicate that:(1)the propagation of surface cracks in transverse and longitudinal direction is dominated by deflection load.In the course of crack propagation,K2 first increases to the top then drops down slowly.In the initial crack propagation,the difference of K2 is small,but in latter phases,K2 in longitudinal direction is greater than that in transverse direction.(2)Among all the parameters of each road surface structure,the most important influence factors affecting the crack extend are thickness h1,modulus E1 and base modulus E2.Other parameters,such as subgrade modulus E0,sub-base thickness h3,modulus E3,and base thickness h2 have little effect.