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在场地波速测量中,由于噪声等因素的影响,很难准确识别P波、S波的初至时刻,致使波速结果存在很大的误差。本文给出了一种基于小波变换的波速测量的新方法。该方法利用波动信号的小波变换与弹性波群速度的关系准确识别弹性波初至时刻。弹性波小波变换的峰值时刻代表着以群速度传播的弹性波的初至时刻,使P波、S波的初至时刻的确定具有明确的物理意义,波速的结果准确、可靠、稳定。此外,利用波动信号的小波多尺度分析,还可以确定地层中传播的弹性波的频散特性。最后,该方法在场地波速测量的实测信号的应用表明,该方法可准确确定P波和S波速度。
In the field velocity measurement, due to the influence of noise and other factors, it is very difficult to accurately identify the first arrival time of the P wave and the S wave, resulting in a large error in the wave velocity result. This paper presents a new method of wave velocity measurement based on wavelet transform. The method accurately identifies the arrival time of the elastic wave by using the relationship between the wavelet transform of the wobble signal and the elastic wave group velocity. The peak time of the elastic wave wavelet transform represents the first arrival time of the elastic wave propagating at the group velocity so that the determination of the first arrival time of the P wave and the S wave has a definite physical meaning and the result of the wave velocity is accurate, reliable and stable. In addition, the wavelet multi-scale analysis of fluctuating signals can also determine the dispersion characteristics of elastic waves propagating in the formation. Finally, the application of the method to the measured signal of the field velocity measurement shows that the method can accurately determine the P-wave and S-wave velocities.