Fall of ground study using seismic hazard assessment methods for an underground mine

Abstract

This article proposes to evaluate the application of Seismic Hazard methodologies for the study of falls of ground (FOG) that occurred in the Cuiabá underground mine. Specifically, a fall of ground that occurred in 2018 in the Serrotinho mineralized body (level 18) was elected as the object of study, since it had characteristics common to other FOGs that occurred deep in the mine. Because of the close proximity and timing of the events, another three FOGs were considered in order to understand the relationship between these rock detachment events and microseismicity. Regarding seismic hazard methods, the apparent stress ratio (ASR) could provide an overview of the evolution of apparent stress in the region. The interpolation of the ASR of microseismic events to the mine levels, in 3 of the 4 cases studied, mapped the FOG region as having a high apparent stress ratio before its occurrence. A rockburst early warning methodology, in turn, proved to be helpful in the identification of precursor conditions of a microseismic event of greater local magnitude (M_L = 0.5) in the analyzed period. Although, during application of this method, some difficulties were found in identifying the right precursors patterns of the microseismic parameters.

Keywords:
underground mining; microseismic monitoring; fall of ground