中文摘要：

利用工业CT获取沥青混凝土试件内部结构断层图像,通过数字图像处理手段将图像内颗粒的二维轮廓提取出来,采用傅里叶描述子表征颗粒轮廓,结合等效直径概念确定了合理的采样间隔角度,对傅里叶变换阶数n的取值进行了定性的分析,并用图形及决定系数R2来描述拟合优劣程度,分析了可能失效的情形。采用球面调和变换对颗粒的三维表面轮廓进行表征,分别对球面调和变换阶数n′及采样点的不同取值效果利用三维可视化进行了比较,探索了其R2随阶数n′及采样点大小的变化规律。结果表明：阶数n′取25～30比较合适;球面调和变换可以更准确地表征集料颗粒的三维轮廓及局部细观特征,并且颗粒的三维轮廓用此方式表征有利于计算机建模的需要,有利于混凝土虚拟试验工作的深入开展。

英文摘要：

X-ray computed tomography（CT） was used to get the cross section images of asphalt concrete specimen.Two-dimensional profiles of aggregates were extracted by a series of digital image processing methods.The Fourier descriptors were used to represent the particle profile.Combined with the concept of equivalent diameter,the reasonable sampling intervals were determined,the value of n was qualitatively analyzed,the goodness and degradation of fit were described by coefficient of determination R2 and graphs,the possible failure case was analyzed.The spherical harmonics transformation was used to represent the 3-D surface profile of particles,the 3-D visualization results of different spherical harmonics transformation values n′ and different sampling points were compared,changing rule of R2 with n and sampling points was discovered.Results show that the value of n′ is more appropriate to take 25 to 30.The spherical harmonics transformation can describe the 3-D surface profile and local meso-scale characteristic of aggregate particles more accurately,and representing the aggregates by this way is beneficial to the need of computer modeling,and it is beneficial to future virtual experiment work on concrete.