论文部分内容阅读
介绍了一种提高单孔法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。互相关分析可求取两相似信号的到时差,但当两信号相似性比较差时,所求得到时差的误差较大;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来求取两相似信号的到时差。试验表明:相比互相关函数,多重互相关函数可改善触发信号和井中三分向探头输出信号的相似性及更好地抑制噪声,因此能更精确地计算出触发信号和井中三分向探头输出信号的的到时差。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。
A new method to improve the measurement accuracy of shear wave velocity in single hole method - multiple cross correlation function method is introduced. 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. Cross-correlation analysis can obtain the arrival time difference of two similar signals, but when the similarity between the two signals is relatively poor, the error of the obtained time difference is larger. The autocorrelation function itself can perform multiple autocorrelation analysis, and the cross-correlation function combined with multiple autocorrelation Function, you can also conduct multiple cross-correlation analysis to find the time difference between two similar signals. Experiments show that the multiple cross-correlation function can improve the similarity between the trigger signal and the output signal of the three-way probe in the well and restrain the noise better than the cross-correlation function, so the trigger signal and the three-point probe in the well can be calculated more accurately The time difference of the output signal. 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.