【摘要】 当前利用CT研究混凝土处于"观察研究阶段",未能对CT试验资料进行定量地描述,严重浪费了CT数资源。本文利用与CT扫描仪配套的便携式动力加载设备,进行了混凝土动力加载实时扫描试验;记录了混凝土动力加载破坏的全过程。根据所获混凝土各受力阶段的CT扫描图,借助于数字图像处理技术和差分盒维数方法,得出了混凝土试样的裂纹演化图像,并计算了试样CT扫描图的分形维数,从细观层面上对混凝土在动荷载作用下的裂纹演化规律进行了定量化研究。在动力单轴压缩荷载作用下,混凝土试样的裂纹穿越骨料追随能量释放最快路径发展;混凝土试样的CT扫描图像有很好的分形特征;以分形维数建立的损伤变量能较好地反映出混凝土试样损伤裂纹的演化规律;分形维数可作为研究混凝土裂纹演化的定量参数。更多还原

【Abstract】 The current studies of the concrete mechanic behavior using CT scan images are not quantitative but qualitative. The resource of the concrete CT data is wasted seriously. In this study,the dynamic loading equipment combined with the X-Ray CT scanner was used to process the real-time scanning test on the concrete samples. The whole rupture process of the concrete samples was recorded. According to the CT images of the concrete samples obtained for each loading step,the crack evolution images of the concrete samples were obtained using the digital image processing technology,and the fractal dimension of the CT slice figure was calculated via the method of Differential Box Counting( DBC). Finally,the mesoscopic crack evolution law of the concrete samples was analyzed quantitatively. It can be concluded that,the crack propagation of the concrete samples under the condition of dynamic uniaxial compression is passes through the aggregate,and follows the fastest path in which the energy is released. The CT images have very good fractal feature. The crack evolution law of the concrete samples can be reflected by the damage variable which is established by the fractal dimension. The fractal dimension can be used as a quantitative parameter to analyze the crack evolution law of the concrete.更多还原