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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。
The paper introduces a new method to improve the measurement accuracy of shear wave velocity - multiple cross correlation function method. Taking into account the difficulty of judging the shear wave to the time difference in the field, a multi-cross correlation function is proposed to obtain the arrival time of two shear waves. For a signal with relatively large noise, multiple autocorrelation analysis is needed to achieve a high signal-to-noise ratio. Cross-correlation analysis can find the time difference between two similar signals, but when the two signals have relatively large noise, Larger; autocorrelation function itself can be multiple autocorrelation analysis, cross-correlation function combined with multiple autocorrelation functions, but also can carry out multiple cross-correlation analysis. Experiments show that the multiple cross-correlation function can improve the signal-to-noise ratio of the trigger signal and the output signal of the three-way probe in the well and accurately identify their arrival time differences. Based on this principle, a test system of shear wave velocity is designed. The system can automatically analyze the shear wave velocity and form a complete report.