Rockburst mechanism and control in coal seam with both syncline and hard strata

The rockburst, that is one of the leading disasters in mining and rock engineering causing serious casualties and property losses, frequently occurs with various features and complex evolution mechanisms. Thus, it is difficult to prevent such disasters. In this paper, evolution mechanisms of two rockburst cases of different types were outlined through microseismicity, energy density clouds and seismic velocity tomography. Measures of caving mining, deep-hole blasting and large-diameter hole were then proposed for risk control of future rockburst disasters during subsequent mining activities. Long-term tremor activities were analyzed to verify the effectiveness of these controlling measures. The results indicate that static and dynamic stresses had played different roles in the two rockbursts. Compared to the first 6.26 rockburst, an obvious characteristic of progressive development of tremors occurred before the 10.15 rockburst. In subsequent mining, controlling measures were proved effective by energy density clouds and seismic velocity tomography. No rockburst happened due to the hard roof and syncline structure again. Only an energy density cloud with small intensity appeared, augmented and then disappeared at the same location where the 10.15 rockburst occurred. The conclusions could expand the understanding of rockburst mechanisms and provide significant theoretical reference for rockburst prevention.