爆破震动信号的小波分析与HHT变换

Wavelet analysis and Hilbert-Huang transform of blasting vibration signal

以实测的爆破震动信号为例,分别应用小波分析和HHT(Hilbert-Huang Transform)变换从不同方面进行对比分析,讨论了爆破震动信号的特征提取和时频分布。结果表明:小波分析和HHT变换都是处理非平稳信号的两种好方法,都能很好地提取信号的主要特征信息和进行滤波、消噪。然而,小波分析存在选择小波基的困难,而HHT变换不需要预先选择基函数,其EMD(empirical mode decomposition)得到的IMF(intrinsic mode function)能反映原始信号的固有特性,通常具有实际物理意义;小波谱的能量在频率范围内分布较宽,而Hilbert能量谱能清晰地表明能量随时频的具体分布,大部分能量都集中在有限的能量谱线上;小波分析中时间、频率分辨率受Heisenberg测不准原理的限制,而HHT变换中时间分辨率不变且精度很高,其频率分辨率则可随信号内在的特性进行自适应调节。分析表明:HHT变换在分析非平稳信号时较小波分析更具适应性,在岩石中波的传播、衰减规律、结构动态响应特征和爆破震动破坏等研究中有着广阔的应用前景。

By means of wavelet transform （WT） and Hilbert-Huang Transform （HHT）, a practical blasting vibration signal was analyzed and the presented results show that both WT and HHT are efficient ways for analyzing and processing non-stationary signals, and can draw main characteristic information from signals as well as carry out wave filtration and noise elimination. In HHT the intrinsic mode function （IMF） obtained with empirical mode decomposition （EMD） can reflect the intrinsic physical characteristics of original data and it has no need of using base functions, while in WT selecting mother wavelet is a difficulty problem. Hilbert energy spectrum can clearly express the energy distribution with time and frequency in detail, and most energy are concentrated in a definitive range of time and frequency, but that of wavelet spectrum lines are distributed in a wider frequency range. Besides, the resolving power of time and frequency is restricted from Heisenberg principle in wavelet analysis, while in HHT time resolving power is precise and steady, and frequency resolving is adaptive according to signal intrinsic characteristics. Conclusion can be made that the HHT method is more adaptive than WT analysis in analyzing non-stationary signals and has a wide application on wave in rock transmitting, attenuation law, restructure dynamic response characteristics and blasting vibration damage.