【作者】 李芬；

【导师】 沈成武；

【作者基本信息】 武汉理工大学 ， 道路与铁道工程， 2006， 博士

【摘要】 本文从细观角度出发将沥青混凝土视为集料、沥青基质和孔隙组成的三相复合材料，通过对沥青混凝土水破坏的宏细观试验，对沥青混凝土水破坏进行了研究。在此基础上实现了沥青混凝土材料细观结构的建模，并对其水破坏过程进行数值模拟。 通过定量分析沥青混合料内部结构的变化更好地掌握了水破坏机理。比较试件无水与饱水状态下的疲劳破坏现象：在宏观裂隙上无水为劈裂，饱水为剪裂；在细观结构上，无水疲劳破坏过程中沥青基质面积稍有增加，而饱水疲劳的沥青基质面积明显减小。反映出水破坏过程中沥青从集料上剥落的过程，即从细观层面上反映出了沥青混凝土水破坏机理。且试件裂纹的演化、发展与其初始空隙分布和集料的长轴取向密切相关。同时在试验过程中采用超声波技术进行沥青混凝土的探伤研究。获取沥青混合料在载荷作用和环境影响后的损伤与声速变化之间的关系，用试件断面孔隙率变化来表征沥青混凝土的损伤，试验结果表明沥青混凝土损伤与超声波速降低之间具有较好的指数关系；并采用超声波技术检测沥青混凝土裂缝深度，为定量评价路面早期损坏程度提供了依据。 本文还采用分形理论对混合料内部结构的复杂程度进行了量化，即沥青混合料断面CT图像不同的分形维数反映出断面的复杂程度不同。采用细观结构分维值和孔隙率变化作为研究细观缺陷演化的定量指标，对沥青混合料疲劳损伤演化过程进行了研究，并得出相应的损伤演化方程。 在试验研究的基础上，本文提出了一种考虑沥青混凝土材料真实细观结构的二维数值分析方法，研究沥青混合料在单轴压缩下的破坏过程，模拟了沥青混凝土材料从裂纹的萌生、扩展、贯通直到宏观裂纹产生导致破坏的过程，模拟结果与CT试验结果进行了对比分析，取得较好的模拟效果，表明建立的细观模型可应用于该材料的力学性能和破坏过程研究。在考虑孔隙水压力后的水破坏数值模拟结果表明，沥青混合料内部裂纹的扩展不仅与细观结构有关，还受到孔隙水压力的影响。饱水状态下沥青混合料内部形成的裂缝过程区比无水状态下形成的裂缝长且发育得较宽，反映有水的条件下试件更易发生破坏，因而疲劳寿命大大缩短。在二维细观模型的基础上，进一步更多还原

【Abstract】 With the rapid development of expressway construction, great attention has been paid to the research of asphalt pavement technology. The water damage issue has always been the focus in global. In the paper, asphalt concrete is taken as three-phase composites consisting of aggregate, mastic asphalt and void based on meso-mechanics. Combine with image treatment technology, the water damage of asphalt concrete is studied through macro-test and meso-test method. And then, the model of meso-mechanics damage of asphalt concrete is presented based on meso-structure images. Numerical simulation of water damage of asphalt concrete is finished.The macroscopically mechanism of water damage is more clearly grasped by the quantitative analysis of the internal structure. According to CT image processing result, internal structure change tendency of the test specimens is analyzed in the process of without water and saturation water fatigue testing of asphalt concrete. The distinguish of the saturation water and without water fatigue testing: The macroscopically crack shape of saturation water is a shear damage, another crack of without water is splitting damage; The difference on the meso-structure lies in: the area of mastic asphalt increases under without water fatigue testing, the area of mastic asphalt obviously reduce under saturation water fatigue testing. The result had reflected the test specimens the mechanism of water damage in the saturation water fatigue testing, namely the asphalt concrete cohesion damage (asphalt film raveling, aggregate exposed area increased gradually). And crack of test specimens evolution、 development have correlate with initial void distribution and major axis orientation of aggregate. At the same time, the damage of asphalt concrete is experimentally studied by ultrasonic technology. The ultrasonic velocity of test specimens is measured before and after fatigue experiment. The relationship between the damage and the descent of ultrasonic velocity is established by damage parameter is defined. According to experimental data, the damage parameter is found to be in更多还原