Time‐frequency domain correlation method based on the synchrosqueezed wavelet transform for tunnel vibroseis and its application

Abstract

To meet the demand for long‐distance and highly accurate detection in tunnel construction, a vibroseis source has been introduced into tunnel forward prospecting. However, serious noise in tunnels reduces the resolution of vibroseis signals, and small‐scale structure recognition in tunnels requires higher signal resolution. Thus, we develop a time‐frequency domain correlation method based on the synchrosqueezed wavelet transform for tunnel vibroseis data. Time‐frequency domain correlation may capture more information than a single time or frequency domain correlation method, and its effectiveness depends on the time‐frequency transformation method. The synchrosqueezed wavelet transform allows us to obtain high‐resolution time‐frequency spectra and thus helps to extract high‐resolution effective signals. The advantages and disadvantages of different correlation methods are highlighted using numerical examples, in which the high resolution and strong robustness of the time‐frequency domain correlation method based on the synchrosqueezed wavelet transform are demonstrated. A detailed field case study in an iron mine tunnel further demonstrates the reliability of the time‐frequency domain correlation method based on the synchrosqueezed wavelet transform for practical data.