膨胀土声波信号能量特征的小波包分析

Application of the wavelet packet method in the frequency band energy distribution of expansive soil acoustic signals

利用小波包分析技术，研究干湿循环作用下膨胀土声波信号的能量分布特征和膨胀土信号中不同频带能量的分布规律。研究结果表明：膨胀土声波信号是一种典型的非平稳信号，具有持时短和突变快等特点。膨胀土声波信号能量在频域上分布广泛，能量分布集中在0～125kHz。在传播的过程中能量衰减迅速。超声波在膨胀土内部传播时高频能量的变化和能量中心的偏移与膨胀土裂隙变化密切相关。随着循环次数的增加，高频成分能量逐渐衰减，能量中心不断向低频端偏移。经过6次干湿循环之后，膨胀土声波信号的能量分布趋于稳定，主要在30～65kHz频段。

Wavelet packet analysis technique has been used to study the energy distribu- tion characteristics of expansive soil acoustic signals and the energy distribution of different frequency bands in the expansive soil under the action of wet and dry cycles.The results show that expansive soil acoustic wave signal is a typical non-stationary signal, which has the characteristics of short duration and fast mutation.Expansive soil acoustic signal energy is distributed widely in the frequency domain, the energy distribution is mainly distributed in the 0- 125 kHz, and the energy decays rapidly in the process of spreading.The changes of high frequency energy and the shift of the center of the energy center are closely related to the crack of expansive soil. With increasing number of cycles, the energy of high frequency component gradually decays, the energy center contin- uously shifts to the low frequency end. After 6 times of dry wet cycle, expansive soil of the acoustic signal energy distribution tends to be stable, mainly distributed in the 30 65 kHz bands.