岩体爆破损伤声波测试信号频谱特征的小波(包)分析

 岩体爆破损伤特性除了影响声波速度外，同时造成声波能量衰减和频谱特征的变化。为弥补单纯声波速度分析的不足，更好地利用岩体声波信号携带的丰富信息，在某地下工程围岩中开展10次小药量模拟爆破岩体损伤声波测试研究。针对傅立叶分析的缺陷，运用小波(包)变换方法，对声波测试信号的频谱特征进行分解分析。研究结果表明：(1) 经小波(包)变换得到的爆破前后岩体声波频谱特征变化规律非常明显；(2) 2–4，2–5和2–6尺度下小波分量的幅值和功率谱密度远大于其他尺度下的小波分量的幅值和功率谱密度，对岩体爆破损伤的敏感性较好；(3) 岩体爆破损伤作用导致声波测试信号的能量集中区和最大能量分布百分比对应的频段(频率)向低频方向偏移。研究成果对于揭示岩体爆破损伤与声波测试信号频谱特征之间的内在联系具有一定的指导意义。

ANALYSIS OF ACOUSTIC WAVE FREQUENCY SPECTRUM CHARACTERS OF ROCK MASS UNDER BLASTING DAMAGE BASED ON WAVELET(PACKET) TRANSFORMATION

The blasting damage of rock mass results in the change of energy attenuation and its frequency spectrum，besides influences on the acoustic velocity. In order to make the best of the plentiful information taken by the acoustic signals of rock mass and remedy the shortage of simple acoustic velocity analysis，the research on the rock mass damage under simulative blasting with little charge for ten times by acoustic measurement in the surrounding rock of some underground engineering is carried out. And the acoustic wave frequency spectrum characters are decomposed to be analyzed with the wavelet(packet) transformation methods，in view of the deficiency of Fourier analysis. Research results show that the variety law of rock mass acoustic wave frequency spectrum obtained by wavelet(packet) transformation is more obvious after blasting. The amplitudes and power spectral density of wavelet components with 2–4，2–5 and 2–6 scale are far higher than those with other scales；and these wavelet components are more sensitive to the blasting damage of rock mass. The acoustic signals of frequency corresponding to the energy concentration area and the distribution percentage of most energy turn to lower as the result of the blasting damage of rock mass. The obtained research results will provide an important reference to reveal the internal relations of the blasting damage of rock mass and the acoustic signals frequency spectrum characters.