软硬交错层理状岩石变角度劈裂的变形场及声发射频率特征

Deformation field and AE frequency characteristics of variable angle splitting of soft and hard staggered bedded rocks

为了了解宏观裂纹以不同角度穿越软硬交互层时岩石的变形场及声发射特征,以天然软硬交互层理状岩石为研究对象,分别开展劈裂方向与层理方向呈0°,30°,60°,90°的劈裂试验。试验过程中辅以数字散斑技术记录变形场,PCI-2型声发射采集仪记录声发射信号。绘制横向受拉区域变形时程图与声发射峰频分布时程图,对比研究发现:劈裂方向与层理方向夹角为0°时,横向受拉区域分布集中,声发射信号峰频点集中在40k Hz附近;夹角为30°和60°时,受拉区域杂乱分散,受载过程中新出现峰频段集中在100,150 kHz附近的声发射信号;夹角为90°时,受拉区域分布较为集中,受载过程中新增加峰频在260 kHz附近的信号。随着岩石层理夹角由低至高的变化,受拉变形区分布形态经历了集中分布—无规则分布—较为集中分布的趋势,而声发射信号峰频带分布则愈加复杂。基于试验结果,讨论了岩石内部破裂源模式与声发射峰频间的关系。

In order to find out the deformation field and acoustic emission(AE)characteristics of rock when macroscopic cracks pass through soft-hard interaction layers at different angles,with natural soft and hard staggered rocks as research object,splitting tests have been carried out with the splitting direction and bedding direction of 0°,30°,60° and 90°respectively.During the experiment,the digital image correlation(DIC)technique was used to record the deformation field,and the PCI-2 AE acquisition instrument was used to record the AE signals.The deformation time charts of the transverse tension zones and the AE peak frequency distribution time charts were drawn.The comparison has shown that when the included angle between splitting direction and bedding direction is 0°,the transverse tension zones are concentrated,and the peak frequency bands of the AE signals are concentrated around 40 kHz;when the angle is 30° and 60°,the tension zones are disorganized,and the new peak frequency bands are concentrated in the 100 kHz and 150 kHz in the loading process;when the angle is 90°,the distribution of tension areas are more concentrated than those in 30°and 60°,and the signals with peak frequency near 260 k Hz are newly increased in the process of loading.As rock bedding angle increases,the distribution pattern of tensile deformation zones experiences a trend of concentrated distribution,irregular distribution,and more concentrated distribution,but the peak bands distribution of AE signals become more complex.Based on the experimental results,the relationship between the modes of internal fracture source and the peak frequency of AE is discussed.