基于小波包分析的爆破振动危害评价初探

结合振动主频的质点振速判据是对单一质点振速判据的补充和完善.但该判据的振动主频是通过FFT变换的频谱分析的方法获得的,不能体现爆破振动波形的多主振频带特征,而且由于方法本身的局限性使得主振频率发生的时间段不能确定.小波包分析法则克服了FFT频谱分析的局限,有效地分解和重构原始信号中的细节信号,并将其作为评价不同频率细节信号的爆破振动危害效果的基础.本文针对爆破振动的小波包分析法进行了研究,对各小波包细节信号加载条件下的不同危害效果进行了讨论,得到了相应的质点振速判据,并将该方法所得到的判据与FFT变换的频谱分析方法所得到的判据进行了对比.结果表明,基于小波包分析法的质点振速判据更加符合爆破振动危害的真实情况.

A PROBE ON DETRIMENTAL EVALUATION OF BLAST VIBRATION BASED ON WAVELET PACKETS ANALYSIS

The present paper intends to make a discussion on the different harm effects of the detailed signals in the different Dominant Frequency Bands through wavelet packets analysis, based on the criteria of Peak Particle Velocity deduced from studies in hope to reduce the actual status of blasting vibration damage. Furthermore, the study cases on the slopes of Tongshankou Copper Mine, Gushan Iron Mine and Hainan Iron Mine justified the above mentioned conclusion. The safety criteria of the Peak Particle Velocity in view of the Dominant Frequency are some supplementary and consummate to the criteria of unitary Peak Particle Velocity. Nevertheless, this kind of Dominant Frequency can be deduced only from the frequency spectrum analysis based on the Fast Fourier Transform (FFT), which is actually not characteristic of the property of multiple Dominant Frequency Band for its intrinsic limitation and failure to work out the reliable time duration in conformity with the Dominant Frequency. However, since the wavelet packets analysis can help to overcome the above mentioned limitation with FFT spectrum analysis and decompose the original signals into the detailed ones with different frequency bandwidths, the decomposition should be the basis of the above mentioned evaluation. The detailed signal waveforms deduced from the said decomposition and reconstruction may represent the vibration time duration series in the different scopes of the Dominant Frequency Band. Therefore, the harm evaluation method based on the wavelet packets analysis can particularly involve all the accounts into the effect of the different Dominant Frequencies on the decision of the evaluation criterion with regard to the value of the detailed signal waveform amplitudes for the measurement of peak amplitude vibration in situs.