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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,所以对处于细观尺度的微裂纹特征进行量化分析,对于理解花岗岩的动力特性有一定的意义。首先利用RMT-150B多功能全自动刚性岩石伺服试验机,采用振幅为10 MPa,频率分别为0.01、0.02、0.05、0.10、0.20、0.50、1.00 Hz的正弦循环荷载作为动力扰动,对海南昌江花岗岩试样进行单轴循环荷载试验。然后,利用扫描电镜(SEM)拍摄得到花岗岩的大量细观结构图片,运用数字图像技术获取微裂纹的细观几何信息,从方位角、长度、宽度和面积对不同荷载频率相应的花岗岩细观尺度微裂纹特征进行量化分析。研究结果表明,随着循环荷载频率的增加,微裂纹方位角发育离散性增加,而其统计均值则在某一区间内波动;微裂纹长度的发育则较快,而仅当荷载频率达到1 Hz时,宽度才有一定的发展,同时,能量耗散的方式也发生一定的变化。
The macro-scale fatigue failure of granite is caused by the initiation, development and penetration of microcracks at the mesoscale. Therefore, the quantitative analysis of the characteristics of the microcracks at the mesoscale scales is of some significance for understanding the dynamic characteristics of granite. First of all, using the RMT-150B multi-functional automatic rigid rock servo testing machine, a sinusoidal cyclic loading with amplitudes of 10 MPa and frequencies of 0.01, 0.02, 0.05, 0.10, 0.20, 0.50 and 1.00 Hz respectively was used as the dynamic disturbance. Uniaxial cyclic loading test specimens. Then, a great deal of mesostructural images of granite were obtained by scanning electron microscope (SEM). The mesoscopic geometry information of microcracks was obtained by using digital image technology. The mesoscale, length, width and area of granite with different loading frequency Microcracking features were quantified. The results show that as the cyclic loading frequency increases, the dispersion of azimuthal microcracks increases, while the statistical mean value fluctuates within a certain range. The development of microcrack length is fast, and only when the load frequency reaches 1 Hz When the width of a certain degree of development, at the same time, the way the energy dissipation has also undergone some changes.