中文摘要：

在循环荷载作用下，花岗岩宏观尺度疲劳破坏是由于细观尺度微裂纹的萌生、发育和贯通引起的，因此对处于细观尺度的微裂隙进行量化分析，对于理解花岗岩的动力特性有一定的意义。利用扫描电镜（SEM）拍摄得到昌江花岗岩的大量细观结构图片，利用数字图像技术对图片进行处理，提取微裂纹的细观几何信息。从矿物晶体和微损伤形式两个角度定量分析了循环荷载作用过程中的细观损伤特征。研究结果表明：①循环荷载作用过程中穿晶裂纹大部分出现在长石晶体内，而云母晶体则以沿晶裂纹为主；②在3类微裂纹中以沿晶裂纹发育速度最快，是疲劳损伤中主要的损伤形式；③沿晶裂纹和穿晶裂纹发展中所消耗能量占微裂纹开裂能量的大部分。

英文摘要：

The failure damage of granite under cyclic load are caused by the propagation and coalescent of cracks at mesoscale; so it is helpful to understand the mechanical behaviours of rock by quantitatively investigating the meso-damage of granite. A great deal of mesostructural images of Changjiang granite in Hainan Province have been obtained by means of scanning electron microscopy（SEM）. The mesostructural images of marble are processed by regional growing theory based on image processing technique. The meso-damage information of granite microcracks are obtained from SEM images. Then, the mesostructural information of microcracks is analyzed by statistical theory and the distribution regularities of microcrack parameters are proposed. Quantitative analyses of meso-damage characteristics under cyclic load are made from minerals and microcracks. It is shown that most oftransgranular cracks are mainly concentrated within the feldspars and microcracks are initiated as boundary and intragranular cracks around micas. And the major meso-damage of fatigue damage is intragranular cracks. The energy of the development of transgranular cracks and intragranular cracks account for most of the micro-crack initiation energy consumption.