The 4th International Symposium on Mine Safety Science and Engineering (ISMSSE2018)

363 / 2018-05-31 09:12:59

Characteristics in nucleation of microseismic events before mining-induced rockburst: two case studies in Hegang coalfield, Heilongjiang province, China

Induced seismology, Energy density index, Tomography, Hegang coalfield, fracture propagation, microseismic events

Mine Dynamics Disaster > Rock burst impact

Relationship between spatial activities of tremors and the occurrence of two rockbursts in Hegang coalfield was revealed using the index of spatial energy density. The stress changes associated with the tremor activities were characterised by seismic velocity tomography. Then, spatial breeding journey of rockbursts was inferred. The results showed that the tremors were distributed in a spatially complicated fashion, and their evolution law over time was difficult to be identified. Energy density clouds had obvious nucleation characteristics, and presented an obvious extension around the nucleuses until strong tremers happened in their edges. The evolution of energy density clouds and the stress changes characterized by seismic velocity tomography showed spatial breeding journey of the rockburst, in which the jump of stress in local areas of rock masses resulted in the clustering and nucleation of micro-fractures firstly, then the micro-fractures developed from disorder to order, and finally with the increase of stress and the development of micro-fractures, macro-fractures appeared, triggering strong tremors and the followed rockburst.