Main disaster-causing strata of composite hard roof and bidirectional, high-low position blasting technology for rockburst prevention

Abstract Theoretical analysis, micro-seismic monitoring, and on-site research were used to examine the main disaster-causing strata of composite hard roof, with a particular focus on rockburst in the working face of thick coal seams. A bidirectional, high-low position blasting technology was proposed for rockburst prevention based on the fracture mechanism of composite hard roof. The effectiveness of this method was verified through on-site, micro-seismic monitoring data. The key findings are as follows. (1) The fracture disturbance zone of composite hard roof was 0–117 m above the coal seam; the strong disturbance zone was 0–32 m above the coal seam; the main disaster-causing strata were 0–40 m above. (2) A bidirectional, high-low position blasting technology for composite hard roof was designed. High-low level blasting on the goaf and solid coal sides intensified roof blasting to lower the risk of high-energy vibration events in the disaster layer, which prevented rockburst in practice. The findings provide crucial guidance for ensuring safe mining in rockburst mines and conducting effective hard roof blasting to prevent rockbursts.