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根据计盒维数(CBD)的计算方法,提出了基于三维裂隙的数字体图像计算其分形维数的立方体覆盖法,并用MATLAB软件实现了该算法.利用工业CT扫描获取了不同围压下破坏煤样的数字图像,通过数字图像处理获取裂隙并生成裂隙体图像,应用立方体覆盖法计算三维裂隙的分形维数;通过对破坏煤样块体质量-频率的统计,计算了块度分形维数.两种分形维数分别从裂隙的发育程度和煤样破碎程度来评价煤样的破坏,两种分形维数越大,煤样的破碎程度越高,裂隙越发育,变化趋势具有一致性.结果表明:提出的计算三维裂隙分形维数的立方体覆盖法是可行的,得出的三维裂隙的分形维数可以作为分析裂隙空间分布的定量参数.基于三维裂隙的数字体图像的分形维数还可以用于对裂隙演化过程的定量描述.
According to the calculation method of box counting (CBD), a cube covering method based on three-dimensional fractal digital volume images was proposed to calculate the fractal dimension, and the algorithm was implemented by MATLAB software.Using industrial CT scanning, Digital images of coal samples were taken to obtain fractures and generate fractured images. The fractal dimension of three-dimensional fractures was calculated by cube cover method. The fractal dimension of fractured coal samples The fractal dimension of fractured coal samples are respectively evaluated from the degree of fracture development and the degree of coal sample fragmentation. The larger the two fractal dimensions are, the higher the fracture degree of the coal sample is, and the more the fractures develop, the more consistent the change trend. The results show that the proposed method of calculating cube fractal dimension of three-dimensional fractures is feasible and the fractal dimension of three-dimensional fractures can be used as a quantitative parameter to analyze the spatial distribution of fractures. The fractal dimension of digital fractal images based on three-dimensional fractures also It can be used to describe quantitatively the evolution of fissures.