基于沥青路面早期水损害的水-荷载耦合CT扫描试验和力学响应分析

Analysis of CT Scanning Test and Mechanical Response of Water-load Coupling Based on Asphalt Pavement Early Water Damage

为了研究在水-荷载耦合作用下沥青混合料试件的压缩疲劳破坏过程及其沥青路面结构的动力响应,借助CT扫描技术和图像处理技术,进行了无水和饱水沥青混合料的宏观和微观破坏初步对比分析,定量分析了破坏前后沥青、集料和空隙的变化情况。根据多孔介质理论,对广西典型半刚性沥青路面结构进行了ABAQUS建模和FLAC-3D的计算,分析了无水和饱水两种情况下的力学响应差异。结果表明:沥青混合料试件从无水向饱水转化时,破坏模式从压裂转变为剪切破坏模式;在行车荷载作用下,饱水沥青路面与其无水情况下力学响应特性的不同主要集中在沥青面层深度范围内;相对于无水情况,饱水情况荷载效应作用时间将会成倍增加,且沥青面层拉应力出现激增,使沥青路面更容易产生结构性损坏;饱水情况下的沥青路面层底产生较大的先压后拉的横向应变,导致沥青路面过早产生疲劳开裂。

In order to research the compression fatigue failure process of asphalt mixture specimen and dynamic response of asphalt pavement under water-load coupling effect, with the help of CT scanning and image processing technologies, we preliminary compared the macro and micro failure of both anhydrous and water-saturated asphalt mixture, we also quantitatively analyzed the change situation of asphalt, aggregates and voids pre and post the failure. According to the theory of porous media, we established the ABAQUS model and calculated with FLAC-3D for Guangxi typical semi-rigid asphalt pavement structure, and analyzed the mechanical response difference under both anhydrous and water-saturated situation. The results show that （ 1 ） when asphalt mixture specimen transformed from anhydrous to water-saturated status, the failure mode is changed from fracturing to shear failure; （2） under traffic loads, the difference of mechanical response characteristics between anhydrous and water-saturated asphah pavement is mainly concentrated in the surthce layer; （3） compared with anhydrous condition, the load eft^et action time of saturated asphalt significantly increased, and the tensile stress generated in the asphalt surface layer appeared a surge, will easily lead to structural damage in asphalt pavement; （4） in the saturated case, the bottom of pavement layer produced large alternating lateral strain which is subjected to tension after compressi leading to prenmature fatigue cracking of asphalt pavement.