Reducing Blasting-Induced Ground Vibrations at the Velkolom Čertovy Schody-Západ Quarry

Abstract

The study discusses the use of the electronic initiation system and software modeling to reduce ground vibrations induced by blasting works. The main part compares non-electric and electronic initiation systems, namely how the system-type affects the peak vector sum (PVS). The study evaluates blasting works conducted between 2011 and 2020 at the Velkolom Čertovy schody quarry. KonĘprusy limestone deposit mined from a quarry Velkolom Certovy schody belongs to one of the most significant mining locations in the Czech Republic. The main mining technology used in breaking rock mass at the Velkolom Čertovy schody quarry is blasting (namely bench blasts and overburden blasts). Blasting generates ground vibrations that affect the surroundings of the quarry. The information on ground vibrations is continuously collected at the predetermined measurement sites through a monitoring network. The network constantly monitors peak particle velocity (PPV), PVS, frequency, and other parameters. The key measurement site appears to be Prošek Dome (M15) in the Koneprusy Caves. At this measurement site, the limit value of the PVS is stipulated at 3.0 mm s-1. If this value is exceeded, it is necessary to establish measures which lead to blasting restrictions (e. g. decrease in the weight of the deck charge, bench blast rows reduction). To meet the criteria, the Velkolom Čertovy schody-západ quarry started to use the electronic initiation system (E*STAR) along with the specialized software Paradigm for vibration modeling. This study, using data collected at the measurement sites Prošek Dome (M15) and KonĘprusy No. 19, compares the PVS generated by the non-electric initiation system (Shock*Star) without modeling and by the electronic initiation system (E*STAR) with modeling. As reference years for non-electric initiation were stipulated years 2011, 2012, 2013, and for electronic initiation years 2018, 2019, and 2020. An analysis of 467 bench blasts executed at the quarry was conducted - or rather, the analysis of the PVS values collected at the pre-selected measurement sites. The analysis shows that the average value of the PVS at the measurement site Prošek Dome (M15) decreased from 2.05 mm s-1 to 1.64 mm s-1 when using the electronic initiation system with vibration modeling. The decrease in the PVS value was observed at the measurement site KonĘprusy No. 19 as well, namely from 0.48 mm s-1 to 0.31 mm s-1. In addition, significantly fewer occasions of exceeding the PVS limit value were reported at the measurement site Prošek Dome (M15), specifically from 6.7 % to 2.7 % of the blasting works conducted within the selected reference years. The study also describes fundamental principles of work with the Paradigm software. Based on the vibration analysis, parameters of the bench blasts need to be adjusted: timing, number of deck charges or rows, etc. Finally, the study summarizes the benefits of the electronic initiation system with modeling.