冻融循环作用下沥青混凝土分形断裂特性研究  

FRACTAL FRACTURE CHARACTERISTICS OF ASPHALT CONCRETE UNDER FREEZE-THAW CYCLES

作　　者：王学军[1] 张向东[1] 敬鹏飞 李军[1] WANG Xuejun;ZHANG Xiangdong;JING Pengfei;LI Jun(College of Civil Engineering,Liaoning Technical University,Fuxin 123000,Liaoning,China;School of Energy and Mining Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]辽宁工程技术大学土木工程学院,辽宁阜新123000 [2]中国矿业大学(北京)能源与矿业学院,北京100083

出　　处：《力学与实践》2023年第1期100-112,共13页Mechanics in Engineering

基　　金：国家自然科学基金资助项目(51774166)。

摘　　要：沥青混凝土作为一种主要的路面材料,暴露于外部寒冷环境下冻融损伤是不可避免的。通过对经历不同冻融循环次数的沥青混凝土试件进行CT扫描,采用数字图像处理技术对CT灰度图像进行处理分析,可获得其内部冻融损伤情况。基于分形理论量化表征了冻融循环作用下内部裂纹扩展的几何特征。沥青混凝土经过冻融循环后的断裂韧性被认为是决定其力学性能损伤程度的关键指标,建立了考虑分形特征的临界裂纹应力、应力强度因子和断裂韧性方程。研究发现:平均分形维数反映了冻融循环过程中的波动特征;断裂韧性由裂纹几何参数决定;弹性模量、临界开裂应力及断裂韧性等力学参数随冻融循环次数的增加而逐渐减弱。As one of the main pavement materials, asphalt concrete is inevitably exposed to freezing and thawing damage. Through CT scanning of asphalt concrete specimens undergoing different freeze-thaw cycles,and using digital image processing technology to process and analyze CT gray images, the internal freeze-thaw damage can be obtained. The geometric characteristics of internal crack propagation under freeze-thaw cycle were quantified based on fractal theory. Fracture toughness of asphalt concrete after freeze-thaw cycle is considered as the key index to demontrate the damage degree of its mechanical properties. The critical crack stress, stress intensity factor and fracture toughness equation considering fractal characteristics are established.The results show that the average fractal dimension reflects the fluctuation characteristics of freeze-thaw cycle.Fracture toughness is determined by crack geometry parameters. The mechanical parameters such as elastic modulus, critical cracking stress and fracture toughness gradually decrease with the increase of the number of freeze-thaw cycles.

关 键 词：冻融损伤 CT扫描 数字图像处理 分形维数 断裂韧性 

分 类 号：O346.1[理学—固体力学]