不同岩石受力灾变声发射主频特性试验研究

Experimental Study on Frequency Characteristics of Acoustic Emission in Different Rocks

为探究岩性对岩石加载过程中声发射主频特性的影响,对玄武岩、花岗岩、煤岩3种不同的岩石试样进行单轴压缩试验,研究试样在加载至破裂过程中的声发射信号主频变化特征,结果表明:加载过程中,岩石声发射信号的主频分布与岩石强度密切相关,加载过程中低频信号的占比随着试样强度的增加而减少;玄武岩声发射信号的主频信号主要分布在35～60kHz,花岗岩声发射信号的主频值集中于35～63kHz与15～25kHz频带,而煤岩的声发射信号主频主要分布在30～32kHz,35～65kHz以及15～25kHz三个频带之间;岩石失稳破裂前期,声发射主频分布状态由密集向稀疏转变,并伴随有高频信号,此现象可以作为岩石失稳破裂的前兆。

In order to investigate the effect of lithology on the characteristics of AE main frequency during rock loading, uniaxial compression tests were carried out on three different rock samples of basalt, granite and coal rock. And the changing laws of the main frequency for AE signals were studied during the loading until rock failure. The results showed that, during the load- ing process, the main frequency distribution of the acoustic emission signals was closely related to the rock strength. The pro- portion of the low-frequency signals during the loading process decreased with the increase of the sample strength. The main frequency of basal signals was mainly distributed in 35~60 kHz; the main frequency of the granite signals was concentrated at 35~63 kHz and 15~25 kHz; and the main frequency of the coal rock signal was mainly distributed between 30-32 kHz, 35 --65 kHz and 15-25 kHz. In the early stage of rock failure, the frequency distribution of AE changed from dense to sparse and accompanied by high-frequency signals. This phenomenon could be considered as a premonition to rock failure.