A comparative study of delay time identification by vibration energy analysis in millisecond blasting

This paper presents the abilities of the Hilbert-Huang Transform (HHT) in identifying important features related to millisecond blasting, particularly the detonation times. This method extracts the signal components of intrinsic mode functions (IMFs) via empirical mode decomposition (EMD), and then HHT is applied to IMFs to get the instantaneous energy of the blasting vibration signals. The real delay time can be identified by analyzing the peak distribution of the instantaneous energy. The effectiveness of the proposed method is verified with the blasting vibration signals recorded in a shallow tunnel as a case study presented in this paper. Compared with another commonly accepted method named the Wavelet Transform (WT), the HHT method can have higher resolution and better ability to identify the peak point of signal. The HHT method is also significant for analyzing the attenuation laws of energy propagation in blasting vibration signals and thus encouraging new vibration mitigation strategies in millisecond blasting for future studies. (C) 2013 Elsevier Ltd. All rights reserved.