岩爆过程的声音信号特征研究

 为探究岩爆过程的声音信号特征，采用自主研发的真三轴岩爆试验机系统，在室内实现花岗岩岩样的岩爆过程模拟，并对试验过程中的声音信号进行全程监测，分析岩爆过程声音信号的波形特征、分形特征以及频谱特征。研究结果表明，岩爆的声音信号波形变化特征能够反映岩爆所经历的主要破坏过程，临近岩爆弹射破坏前，存在一段声音信号波形幅值较小的“相对平静期”；岩爆过程的声音信号幅值具有时间分形特性，声音信号幅值分形维数持续增加至峰值后在一段时间内持续下降至最低值可作为岩爆发生的前兆信息；岩爆过程中，不同破坏现象具有不同的声音频谱特征，声音信号主频总体呈“高频向低频迁移”的演化趋势，频谱形状经历“多峰–单峰”的交替变化过程。岩爆过程的声音信号在波形、幅值的时间分形维数、频谱3个方面具有显著特征与内在演化规律，声音信号的变化特征可作为岩爆预测的前兆信息。

Acoustic signal characteristics in rockburst process

In order to explore the characteristics of rockburst acoustic signals，laboratory experiment was conducted to simulate the process of granite rockburst using the true-triaxial rockburst test system developed in-house. The acoustic signals were monitored during the rockburst process. The characteristics of waveform，spectrum and fractal of acoustic signals of rockburst process were studied. The results showed that the variation characteristics of waveform reflected the main failure process of rockburst. In the rockburst process，a relatively quiet period of the acoustic signals，i.e.，the amplitude of waveform becoming quite low close to the moment of rockbursting was discovered. Furthermore，the value of time fractal dimension of amplitude declined continuously to the lowest value after increased to a peak during a period of time can be regarded as an indication of rockburst. During the process of rockburst，different failure phenomena have different spectrum features，the main frequency value of acoustic signals has a tendency of changing from high to low，the spectrum form experience an alternating process of multimodal and unimodal. In conclusion，acoustic signals in rockburst process have distinct characteristics and inner evolution laws on waveform，time fractal dimension of amplitude and frequency spectrum. Therefore，the acoustic signals can be regarded as the precursor information for rockburst prediction.