【摘要】 花岗岩在固体围压三轴压缩下破裂，然后沿主破裂面摩擦滑动（粘滑或稳滑），实验后我们将样品从围压介质铅中剥出来，做成显微薄片，在２０倍显微投影仪下观测其主破裂及裂纹系分布，用尺度法统计并计算裂纹系分维。结果表明，８个样品的无标度区（Ｒ）都相同，但是随尺度变化，分维值表现出分段线性的特征。当０．０５＜Ｒ＜０．１５ｍｍ时，裂纹系分维在１．１２－１．４１之间，主破裂分维在１．０８－１．１５之间；当０．１５＜Ｒ＜７．５ｍｍ时，裂纹系分维在１．４６－１．８３之间，主破裂分维在１．２２－１．５３之间。主破裂和裂纹系分维值都和围压、应变率等实验条件及破裂强度有关。随围压和应变率不同，主破裂和裂纹系发育成不同形态。在实验的８个样品中，可以用分数维来识别裂纹系的形态和微裂纹的多少。更多还原

【Abstract】 After granite fractured under confining solid medium triaxial pressure, friction sliding (stable sliding or stick sliding) occurred along main fracture surfaces. In our study, the distribution of main fractures and a fracture system in microsections was observed by using microprojector (X20), and the fractal dimension of the fracture system was measured and calculated. The results show that the no-scaling zones (R) are the same for eight samples. When Ris between 0.05 mm and 0.15mm, the fractal dimension (D value) of the fracture system is between 1. 12 and 1.41, and D values of the main fracturcs are between 1.08 and 1.15.When R is between 0. 15min and 7.5inm, D values of the fracture system is between 1.46 and 1.83, and D values of the main fractures are related to the fracture strength and test conditions such as confining pressure, strain rate, etc. With different of strain rate and confining pressure, the fracture system appears as different patterns, such as single fracture sytein, the "λ" -shape fracture system or "X"-shape of fracture system. It follows that the D value can be used a parameter to classify fractures.更多还原