岩石声发射信号能量分布特征的EMD分析

Energy distribution characteristics of rock acoustic emission signals with EMD analysis

冲击荷载作用下岩石声发射信号具有瞬态性和多样性的特点,属于典型的非平稳信号。利用EMD方法对岩石声发射信号进行分解,得到一系列具有不同特征时间尺度的IMF分量,对每一个平稳的IMF分量提取能量特征。分析结果表明:冲击荷载作用下岩石声发射信号能量主要分布在前4个IMF分量内,且分布不均匀;岩石声发射信号各IMF分量的频谱与原始信号的频谱基本一致;随着岩石的密度、纵波波速、弹性模量的降低,冲击荷载作用下岩石声发射信号的优势频率越来越集中,且其优势频率有往低频发展的趋势;相比小波包分析,EMD分析法对于非平稳信号而言更具适应性。

Rock acoustic emission signals have transient property and diversity under impact loading, which belong to a typical non-stationary signal. EMD method was used to decompose a rock acoustic emission signal into a number of IMF components with different characteristic time scales and then the energy characteristic of each stationary IMF component was extracted. The test results showed that the energy of a rock acoustic emission signal mainly distributes in the first four IMF components, and distributes unevenly; the frequency spectrum of each IMF component agrees well with the original signal frequency spectrum ; if density of rock, speed of longitudinal wave and its elastic modulus decrease, the dominant frequencies of the rock acoustic emission signal under impact loading become more concentrated and tend to be lower; compared with wavelet packet analysis, EMD analysis is more suitable for non-stationary signals.