Improved signature hole analysis for blast vibration control in open pit mines

Ground vibration is an undesired effect of blasting in mining. In some situations where geotechnical slope performance is of concern, blast design gains an increased relevance as a variable to consider in slope stability. Several methods are available to assess the vibration levels produced by blasting in a mine operation (surface and underground). The scaled distance approach is the most widely used methodology to control vibration, however it has several limitations including the need for a complete set of data to find the ground coefficients used in the governing equation. This paper proposes a new methodology using a case study to predict and control ground vibrations produced by mine blasts based on the concept of the traditional signature hole technique. In the new methodology, a Monte Carlo scheme is used to produce a histogram of the predicted peak particle velocity and acceleration in locations of interest of the slope, according to the geometry, the timing, and the sequence of the blast design. This methodology has been used in surface coal mines to protect important infrastructure (power structures, gas lines, etc.) and in metal mines to control vibration levels to minimize the impact of blasting on the performance of large open pit slopes.