岩石超声波检测信号的小波分析

Wavelet analysis of ultrasonic testing signals in rock

利用小波变换分析岩石超声检测信号,了解岩石内部结构特性和物理力学特性。建立了岩石超声测试实验系统,并进行多分辨率分析。结果表明,小波分析可以对指定频带和时间段内的信号成分进行分析,在时域和频域具有良好的局部化性质。可以准确地抓住瞬变信号的特性,对频率成分采用逐渐精细的时域或空域取样步长,从而聚焦到信号的任意细节。完整岩石试样超声检测信号及其小波变换波谱比较规则,无复杂变化,但反射波衰减较快。不同岩性的岩石,其超声波检测信号无明显差别,其小波变换却不相同,这差异是由于岩石的细观组构不同造成的。小波变换波谱反映了岩石节理、裂隙等岩石的完整程度。

The ultrasonic testing signals in rock based on wavelet ransform is analysed, to understand the structure and physical mechanic characteristic of rock. Ultrasonic testing experiment system of rock is set up. Based on wavelet transform multiresolution is analysed. The results indicate that beneficial information in testing signal is sufficiently used. Wavelet transform has good time frequency localization and can seize character of instantaneous changing signals accurately and focus any details of signal for frequency through gradually meticulous sampling step of time field and frequency field. Ultrasonic testing signal and its wavelet transform in intact rock are regular and has no complicated change, but reflect wave attenuation rapidly. Ultrasonic testing signals of different lithology rock have unconspicuous distinction, whose wavelet transforms are different. These differences are due to distinct microcosmic tissue and structure, so wavelet transform spectrum reflect rock integrity, for example, joints and cranny of rock.