Measurement and analysis of land and water bottom vibrations induced by underwater blasting

In order to investigate the characteristics of the water bottom and land vibration induced by underwater blasting, a water bottom vibrometer was developed and applied to a field measurement test to get actual vibration signals on land and water bottom. The characteristics of the vibration signals were studied in the time domain and frequency domain separately, and the influence of water medium on the land vibrations was specially analyzed by using the frequency order wavelet packets algorithm. It shows that the water bottom vibrometer could collect vibration signals effectively with stable performance. The signal analysis shows that in the same horizontal epic-distance of the same underwater blasting, the water bottom vibration has larger amplitude, higher main frequency and wider frequency band than the land vibration. The land vibration mainly consists of two components that in low frequency caused by direct blasting shock and high frequency caused by water oscillation impact. The water impact vibration components extracted from the land vibration by wavelet packets decomposition algorithm distribute more widely in time domain with earlier peak time than the blasting vibration components, and overlap staggered with each other.