多重互相关函数在剪切波速测量中的应用

论文介绍了一种提高剪切波速测量精度的新方法——多重互相关函数法。考虑到判断场地剪切波到时差的困难,提出了用多重互相关函数来求得两剪切波的到时差。对噪声比较大的信号需要进行多重自相关分析才能达到较高的信噪比;互相关分析可求取两相似信号的到时差,但当两信号噪声比较大时,所求得的到时差误差较大;自相关函数本身可进行多重自相关分析,互相关函数结合多重自相关函数后,也可以进行多重互相关分析。实验表明：多重互相关函数能提高触发信号和井中三分向探头输出信号的信噪比和精确地识别出它们的到时差。基于此原理设计了剪切波波速的测试系统,此系统能自动分析出测点的剪切波速和形成完整的报告。

Application of multiple cross-correlation functions to the measurement of shear-wave velocity

A new method based on the multiple cross-correlation functions for shear-wave velocity measurement in single-hole is introduced. As the difficulty to analyze the arrival time difference of shear-wave velocity, the multiple cross-correlation functions to get the arrival time difference of two similar shear-wave velocities are used. The multiple-auto-correlation functions to the signal with big noise to get the high SNR should be used. The cross-correlation functions could get the arrival time difference of two similar signals, but the error is always too big when the noise of signals is big. The auto-correlation function could do the multiple auto-correlation analyses, and the cross-correlation function could also do the multiple cross-correlation analyses with multiple auto- correlation function. The experiment indicates that the multiple cross-correlation function could increase the SNR and precisely get the arrival time difference of the signals of shear waves acquainted by trigger or by probes. Based on this principle, an expert recognition system to calculate shear-wave velocity is designed, which could automatically analyze the shear-wave velocity of each measured point and form a complete report.