Investigating the effects of bench geometry and delay times on the blast induced vibrations in an open-pit quarry

The paper analyzes the results of research aimed to monitor, predict and minimize the ground vibrations induced by blasting in an open pit limestone quarry in Italy. Data on 135 vibrations taken from 18 production blasts and 2 signature blasts were examined, including the effects of the bench orientations. Blast vibrations at the quarry were monitored for approximately three months. The blast vibration magnitudes and frequencies and their effects were analysed by both the conventional PPV concept and a software that is able to predict the vibration amplitudes of a production blast at the target sites by modelling signature blast data. The results have been rated and classified considering the peak particle velocities (PPV) measured in a number of critical areas near the quarry. A comparative analysis between the results predicted by the software and actual blast results was carried out. The benefits of the software were then highlighted, proving able to predict ground vibrations induced by blasting more reliably than the conventional site laws. Finally, based on the results, some arrangements were provided for two bench geometries employed at the quarry site.