基于变分模态分解的浅层震源聚焦定位方法

Shallow Seismic Sources Focus Location Method Based on Variational Modal Decomposition

针对地下浅层地层结构复杂,地面获取的爆炸波震动信号波形混叠、频散严重,采用逆时聚焦方法震源成像模糊,震源定位精度低的问题,提出基于变分模态分解(VMD)的浅层震源聚焦定位方法。该方法利用爆炸信号的宽频谱特性及高频信号逆时成像更聚焦的优点,反演重建各模态频率分量所对应的三维逆时能量场图像,构建了高精度的能量场聚焦图像,并通过计算聚焦区域的重心得到定位结果。数值仿真实验结果表明,该方法与逆时偏移(RTM)成像相比,成像结果更聚焦且图像更清晰,定位精度也得到了进一步提升。

In view of the complex structure of the shallow underground stratum,the aliasing and serious dispersion of the blast wave vibration signal obtained from the ground,the blur of the source image and the low accuracy of the source location using the reverse time focusing method.,this paper developed a shallow source focus location method based on variational modal decomposition(VMD).This method took the advantages of the wide-spectrum characteristics of the explosive signal and the advantages of more focused reverse-time imaging of high-frequency signals,inversion and reconstruction of the three-dimensional reverse-time energy field image corresponding to each modal frequency component,and constructed a high-precision energy field focused image.The positioning result was obtained by calculating the center of gravity of the focus area.Numerical simulation experiment results showed that,compared with RTM,the imaging results of this method were more focused,the image was clearer,and the positioning accuracy was further improved.