隧道超前地质预报中时频域去噪方法对比研究

A Study on Time-Frequency Domain Denoising Methods in Tunnel Advance Geological Prediction

在隧道超前地质预报数据采集工作中,常会出现空气振动波(声波噪音信号)的干扰,表现为频率高、振幅大、到时晚,并且与地震波反射波信号相互重叠。介绍了时频域短时傅里叶变换、小波变换和S变换,这三种变换数学原理,根据声波与反射波信号在时频域的特征差异性,实现对声波压制,提高反射波信噪比。通过实际数据对比分析了空气振动波对地震记录噪声干扰的机制,利用三种时频域去噪方法对声波进行压制。结果表明,因S变换的时频窗口随频率自适应调整,S变换在隧道超前地质预报中时变滤波效果更好。

The interference of air vibration wave (acoustic noise signal), which is characterized by high fre-quency, large amplitude, late arrival, and overlapping with seismic reflection wave signal, often occurs in the data acquisition of tunnel advance geological prediction. This paper introduces the time-frequency methods to suppress sound noises which include short-time Fourier transform, wavelet transform and S-transform. The mathematical principles of these three transformations can suppress sound waves and improve the signal-to-noise ratio of reflected waves according to the difference in time-frequency characteristics between sound waves and reflected waves. The interference mechanism of air vibration wave to seismic record noise is analyzed through com-parison of actual data, and three time-frequency domain denoising methods are used to suppress acoustic wave. The results show that the time-varying filtering effect of S transform is better in advance geological prediction of tunnel because the time-frequency window of S transform is adaptively adjusted with frequency.