Assessing Rockburst Hazards Using a Self-Developed Real-Time Microseismic Monitoring System in a Deep-Sea Goldmine

Deep-sea mining extracts ores on the ocean floor. During this process the sea water may flood into the mine due to rockburst hazards. This study proposes an effective method to assess rockburst hazards using a self-developed real-Time microseismic monitoring system in Sanshandao goldmine (the first undersea mine in China). In addition, the wave dissimilation patterns of this mine have been elucidated by analyzing the signals obtained by the geophones embedded in a similar material model. The monitoring work started in December 2014 and ended in March 2015 in Sanshandao goldmine. To assess rockburst hazards, this study proposes several indexes including spatial-Temporal distribution of microseismic events, microseismic activity rate, energy release rate, continuity index, and average daily energy. The results show that the surrounding rock went through the stationary, active, secondary stationary, and secondary active periods before rockburst occurrence. Compared with the stationary period, a sudden change of the continuity index and average daily energy can be observed in the active period in which minor rockbursts constantly occurred. Rockburst accidents are very likely to occur in the secondary active period. However, before this period, there usually exists a secondary stationary period without rockburst risk. This study proposes a workflow for designing and applying microseismic monitoring systems.