对含原生隐裂隙的玄武岩试样开展单轴压缩试验,并同步采集岩样变形破坏过程中的声发射信息,结合试样的结构特征对试验结果进行系统分析,研究结果表明:(1)隐裂隙影响试样的压缩破坏特征,试样受原生隐裂隙的切割,其压缩变形破坏模式为隐裂隙尖端裂纹的扩展、裂隙面之间的剪切滑移以及由裂隙面剪切变形而引起张拉破裂等构成的剪切-张拉型变形破坏模式。(2)受原生隐裂隙的影响,试样在变形破坏阶段,应力-应变曲线呈“锯齿”状;(3)含隐裂隙的玄武岩天然平均单轴抗压强度为106MPa,低于同场地完整的隐品质玄武岩;且试样中隐裂隙越发育,其强度越低;(4)加卸载过程中,不同类型的变形所引发的声发射信号特征不一样,永久应变所引发的声发射信号幅值比弹性应变所引发的高;(5)试样在破坏之前,内部破裂较少,声发射数保持平稳,进入变形破坏阶段后,声发射数激增;试样中的隐裂隙对声发射能量具有吸收效应,而当隐裂隙闭合时,吸收效果减弱。
A set of uniaxial compression tests has been carried out on the samples of basalt rock with hidden fissures and the acoustic emission signals have been monitored during the test processes. The failure characteritic of samples under the compression loads are affected by the hidden fissures and the failure mode is primarily the shear-tension failure that the cracks propagated from the tips of hidden fissures, then slide beside the cracks. The hidden fissures cause the stress-strain curve to exhibit a "saw tooth" shape during the failure stage. The average uniaxial compression strength of the tested samples is 106 MPa and lower than the intact aphanitic basalt rock from the same site. The more of fissures within a sample, the lower the strength. The characteristics of acoustic emission signals are affected by the type of strain. The energy acoustic emission caused by the permanent strain has a higher amplitude. The acoustic emission develops steadily before failure, and increases greatly after entering the failure stage. The signal intensity of acoustic emission decreases by the hidden fissures inside the specimens, but the absorption effect dropps when the fissures close under compression.