三轴高应力下花岗岩剪切声发射峰值频率特征

Peak Frequency Characteristics of Acoustic Emission for Granite During Shear Under High Triaxial Stress

采用大型真三轴试验机对花岗岩进行双面剪切试验,试验结果表明:法向应力的改变会引起破坏形式的不同(稳态破坏与非稳态破坏),从而引起峰值频率特征的差异,侧向应力的改变对峰值频率特征无明显影响;剪切变形过程中的声发射峰值频率可分为平静期、起伏期和上升期;峰值频率能够预测岩石的破坏临界点,可以作为判断花岗岩剪切破坏的敏感指标,此外,峰值频率变化特征还可以反映出破坏过程中剪应力的变化情况。

The double-sided shear experiments for granite were carried out by large true triaxial testing machine. The results showed that the change of normal stress would cause different damage modes, including steady damage and unsteady damage, consequently leading to the difference of peak frequency characteristics. But the change of lateral stress had no significant effect on the peak frequency characteristics. The peak frequency of acoustic emission in the process of shear deformation could be di- vided into quiet period, floating period and rising period. And the peak frequency could be used to measure the damage critical point of granite, which could be regarded as a sensitive index for determining the shear damage of granite. Besides, the change characteristics of peak frequency also could reflect the changes of shear stress in the process of damage.