A New Method of Estimating Wave Energy from Ground Vibrations

Abstract

Performance of explosive energy is rated in a number of ways, obtained either from theoretical calculations or from experimental tests. However, it is difficult to determine the amount of the explosive energy transferred to the rock and converted into efficient work in the application of rock blasting. Although measurement of some of the effects of explosive energy in rock mass is ground vibration, noise, etc., which are usually conducted for blast control/analysis purpose, the results are rarely used on energy content. Energy transferred to the rock in the form of seismic waves is called seismic energy. In conventional analysis of blast results, generally, the ground vibrations generated due to blasting operations are monitored at a known distance from blast site with a geophone/ground vibration monitor, in three mutually orthogonal directions. Using such wave forms, an energy component is estimated from all the wave forms in three directions, using a sophisticated signal processing software, which is termed as “wave energy”. The wave energy is compared with the estimated seismic energy. An investigating program was taken up involving 31 blasts conducted at a hard rock excavation site to assess the influence of depth of excavation and scaled distance on the seismic energy wasted in the form of ground vibrations.