Control mechanism and prevention technology for dynamic and static loads in rockburst prevention of backfill mining faces with hard roofs

LI Jiazhuo; YANG Xiaodong; TAN Wenfeng; TONG Peng; KAN Jiliang; REN Wentao; LI Zengqiang; WANG Jian; LI Songyue

doi:10.11799/ce202602016

Abstract：The strong dynamic loads generated by the fracture of hard roofs during face mining and the superposition of high stress from great depth are primary triggers for rockbursts.To investigate the effect of backfill mining on controlling these loads at their source,we employed theoretical calculations and field monitoring to examine the evolution of roof fracture height and the distribution characteristics of abutment pressure under varying backfill compaction rates.A classified prevention and control technology for rockbursts specific to backfill mining was proposed and applied at a deep hard roof face in Gucheng Coal Mine,with the prevention effectiveness verified through field microseismic monitoring.The results indicate that an optimal backfill compaction rate exists for backfill mining faces.After reaching this optimal rate,the movement pattern of the hard roof shifts from periodic fracturing to bending subsidence,significantly reducing the dynamic loads from roof fractures.The decrease in roof fracture height also leads to a reduction in the peak abutment pressure.At the 1123 working face of Gucheng Coal Mine,where the optimal compaction rate was not initially achieved,measures including pre-split blasting of the hard roof,roof coal support,high-pressure grouting of thick roof coal,and large-diameter boreholes were implemented.In contrast,at the 1#working face,which reached the optimal compaction rate,roof-cutting blasting for pressure relief was eliminated,retaining only large-diameter boreholes in the coal mass and pressure relief measures in specific areas.After implementing these measures,the compaction rate at the 1123 working face gradually increased from 70%to 90%,and the occurrence of microseismic events in the roof transitioned from"low-frequency,high-energy"to"high-frequency,low-energy".While that in the 1#working face exhibited"low-frequency,low-energy".