MINING BLAST-INDUCED GROUND MOTIONS IN TAILINGS DAM

Leonardo Santana de Oliveira Dias, Marco Antônio Silva Braga, Alan de Souza Cunha, Gerrit Olivier and Rodrigo Peluci de Figueiredo 

ABSTRACT

Ground motions caused by routine blasting activities represent a concern for mining companies, that face the challenge of producing without causing critical damage to tailings dams, mine pit slopes and waste piles. Few dams in Brazil are monitored by microseismic systems, and there are no references in the literature about monitoring in open pit mine and dam. In order to analyze the ground motion data induced by blats and their relationship with dam stability, it was installed a seismic system, that records events continuously in an array of 16 geophones (14 Hz and 4.5 Hz), 12 installed in an open pit and 4 in a tailings dam with value measurement of Peak Ground Acceleration, Peak Ground Velocity, dominant frequency, and seismic source parameters related to blast events. In the monitored period, sensors from the open pit and dam were analyzed and all accelerations recorded showed that ∼95% of the values are lower than 0.06 m/s2, with 90% of the records with higher dominant frequency (>10 Hz), that presents lower damage potential due to the lower capacity to produce high values of displacements. The system showed the potential to add new data and information to the current dam geotechnical instrumentation.

Keywords: blast-induced seismicity; microseismic monitoring; tailings dam; risk management; geotechnical monitoring plan.