考虑横观各向同性疲劳损伤的沥青路面数值模型

Numerical Model of Asphalt Pavement Considering Transversely Isotropic Fatigue Damage

为研究车辆荷载作用下沥青路面的疲劳损伤问题，假定路面结构内受拉区的疲劳损伤横观各向同性，推导了沥青路面考虑横观各向同性疲劳损伤的本构方程．采用FORTRAN语言开发了材料子程序UMAT，结合有限元分析软件ABAQUS，得到了沥青路面的横观各向同性疲劳损伤数值分析模型．通过对该模型在不同荷载下的疲劳寿命分析，建立了荷载一疲劳寿命曲线，与试验结果进行对比，验证了模型的可靠性，并分析了损伤度及水平拉应力在路面结构内的分布规律．研究结果表明：疲劳损伤主要分布在基层底面双轮中心线附近，该位置最先产生疲劳裂纹，随着荷载作用次数增加，受损区水平拉应力在减小的同时，分布规律也发生了很大的改变，其最大值位置沿道路竖向从基层底面向上移动，沿道路横向从双轮中心线位置往两侧移动；本文方法得到的路面疲劳寿命与试验结果吻合较好，相对误差在4．57％～9．82％之间．

In order to study the fatigue damage in asphalt pavement, the damage that occurred in the tensile zone of pavement structure was assumed as being transversely isotropic. Based on this assumption, the asphalt pavement constitutive equation considering the transversely isotropic fatigue damage was derived. Then, using FORTRAN language to develop a material subroutine and a load subroutine, an ABAQUS finite element model of asphalt pavement was established based on the transversely isotropic fatigue damage theory. By analyzing the fatigue life of the model under different loads, the load-fatigue life curve was established in comparison with the test results to verify the reliability of the model. The distribution of damage degree and horizontal tensile stress in the pavement structure were studied by the finite element model. The results indicate that the fatigue damage mainly distributes at the base bottom near the middle line between the double wheels, where the fatigue crack appears first. With the load cycles increasing, the horizontal tensile stress decreases gradually, and its distribution in pavement structure changes. Its maximum position moves upward from the base bottom and transversely to the two sides from the middle line. The pavement life calculated by the proposed model is in good agreement with the experimental results, and the relative error is between 4.57% and 9.82%.