A STUDY OF THE INFLUENCE OF DIFFERENT BLASTING MODES AND EXPLOSIVE TYPES ON GROUND VIBRATIONS.

In order to assess the variation of ground vibration intensity, if any, due to the use of three different blasting methods and two different types of explosives, a large number of monitored ground vibrations was analysed in an open cut coal mine. This work involved 86 sets of blast data for different types of blasting when ANFO and Slurry explosives were used in this mine . Statistical analysis of the data sets resulted in 5 of the best fitting empirical relationships between peak particle velocity and scaled distance with excellent values of coefficients of correlations. A comparison of the analytical work revealed that the level of ground vibration varies significantly with the changing method of blasting and/or explosive type . The roles of these factors have been quantified. The rate of the vibration reduction, due to the variation of blasting modes and/or explosive type, varies within each blasting method. These rates are higher in lower ranges of scaled distances, but converge to an almost constant rate at certain scaled distances. The range of this rate varies from 45.77% to 89.34% for free face blasting, and from 38.72% to 56.28% for a buffered blast , depending on the explosive type and scaled distance. It was also observed that one of the two site-specific parameters in the empirical vibration criterion is influenced significantly by the variation of the blasting method and explosive type. However, the other parameter is not much affected by these two factors, and is shown to be more loyal to ground conditions.