IMPROVED BLAST VIBRATION ANALYSIS USING THE WAVELET TRANSFORM

Explosive blasting is commonly used for the retrieval of usable materials or to excavate under-ground spaces. One of the most significant side effects produced by the explosive blasting process is the generation of vibrations which propagate through the ground and can travel great distances. Since it is becoming increasingly common for mining sites to be located near urban areas, the generated ground vibrations can induce not only cosmetic and structural damage, but also dis-comfort or injury to residents. Blasting engineers are constantly faced with an unavoidable com-promise; while the purpose of a blast is to fragment as much rock as possible, any increase in the size and energy of the blast can generate larger ground vibrations near the surrounding urban areas. The current monitoring and analysis of ground vibrations due to blasting are simplistic approaches which monitor only the dominant frequency and peak particle velocity of the meas-ured ground vibrations. This paper presents initial research into the use of the wavelet transform to provide an improved approach for investigating and analysing blast-induced ground vibrations. An overview of the two time-frequency methods; the short time Fourier transform, and wavelet transform, is included, along with an outline of the process for selecting a suitable wavelet for blast-induced vibrations. A series of blast-induced vibration records were obtained from a quarry in Wallonia, Belgium, and analysed using the two time-frequency methods for comparison.