基于FE/EFG耦合方法的沥青路面裂纹扩展模拟

SIMULATION OF CRACK PROPAGATION IN ASPHALT PAVEMENTS BY USING THE COUPLED FINITE ELEMENT AND ELEMENT FREE GALERKIN METHOD

沥青路面裂纹在行车荷载下的裂纹扩展规律对于沥青路面的设计、维护具有重要的指导意义.通过预切口沥青混合料小梁疲劳试验,利用无网格伽辽金/有限元耦合方法,对沥青路面表面裂纹扩展进行了数值模拟,研究了面层厚度、面层模量、基层厚度、基层模量对裂纹扩展的影响规律.结果显示:随着预切口距离加载中心距离的增大,沥青混合料小梁的疲劳寿命增大,裂纹尖端的Ⅰ型应力强度因子减小,裂纹所表现出的Ⅱ型特性增强;在沥青路面表面裂纹扩展过程中,应力强度因子经历一个急剧上升,达到一个极值后缓慢下降,然后又缓慢上升,最后急剧增加的过程;随面层、基层厚度的增加,表面裂纹尖端的应力强度因子降低;面层、基层模量对裂纹扩展路径的影响较大.

It＇s very important to the design and maintenance of asphalt pavements that how cracks propagate there under traffic loads. The fatigue test of pre-sawed asphalt concrete beam was carried out, and the simulation of top-down crack propagation in asphalt pavements was conducted by using the coupled finite element and element free Galerkin method （FE/EFG）,in order to study the effects of surface-layer thickness and modulus, grass-roots thickness and modulus on top-down crack propagation. The results show that the beam＇s fatigue life is prolonged with the increase of the horizontal distance between the presawed notch and the loading site,and the stress intensity factor （SIF） of mode Ⅰ at crack tip decreases, while the SIF of mode Ⅱ increases rapidly. The SIF experiences a process,＂sharply increasing- slowly descreasing- slowly increasing- sharply increasing again＂ during the crack propagation. With the thicknesses of surface layer and the grass-roots,the SIFs at surface crack-tips reduce; The modulii of surface layer and grass roots produce greater influence on the crack propagation-path. The deeper the overlay or base, the lower the SIFs. The crack path is obviously affected by the moduli of the overlay and base.