Precursory characteristics of large-scale rockmass collapse based on multiple microseismic parameters

Microseismic monitoring is vital for identification and analysis of precursory characteristics of rockmass failure and collapse, which is of great significance for geological hazard early warning and management. By conducting a quantitative analysis of multiple microseismic parameters based on previous insights from laboratory acoustic emission experiments, we investigate the precursory characteristics of large-scale rockmass collapse associated with the large blast in Shizhuyuan Mine on 21 June, 2012. Both the b-value and spatial fractal dimension exhibit a decreasing trend, and the sharp decrease of b-value and the continuous decline of fractal dimension serve as two discernible precursors of rockmass failure. Besides, the variations in the energy index and cumulative apparent volume reflect the dynamics of stress and strain, respectively. The combination of a decrease of energy index against an increase of cumulative apparent volume also indicates the unstable state of rockmass, and this process may repeat before the final rockmass collapse. This case study demonstrates the significance of microseismic monitoring in providing valuable information for early warning and management of rockmass collapse. This work also provides insights for the safety monitoring of various geological engineering activities involving blasting operations.