Underground hydraulic fracturing with long boreholes for rock burst prevention under thick hard roofs

YAO Zitao; CHEN Xuehui; LI Zhenan; WEI Hongbin; BAI Jianfei; ZHOU Hongwei

doi:10.11799/ce202507012

Abstract：To address the difficulty in large-range pre-relief for rock burst prevention in working faces under thick hard roofs,a study was conducted on hydraulic fracturing technology with long boreholes for rock burst prevention at the No.20101 face of Dahaize Coal Mine.Theoretical analysis and field measurements were carried out,the fracturing layers were identified,and the effects of hydraulic fracturing and rock burst prevention were evaluated.The conclusions are as follows:①By analyzing the height of the caving zone filled with rocks in the goaf and the distribution pattern of microseismic events in the working face,and comprehensively considering the height required to fill the goaf,the fracture range of the overlying strata,and horizon of thick-hard rock strata,the design heights for underground long borehole hydraulic fracturing were determined to be 20 meters and 35 meters,respectively.②During fracturing,the water pressure fluctuates within a stable range,and in the late stage of fracturing,the sudden increase in water output from adjacent boreholes indicates that the fractures in the target layer have connected with adjacent boreholes,forming a fracture network,demonstrating good fracturing results.③After adopting underground long borehole hydraulic fracturing,the total energy and frequency of microseismic events,number of high-energy microseismic events,dynamic load coefficient,and weighting interval have declined significantly.The research results indicate that underground long borehole hydraulic fracturing can significantly reduce the risk of rock burst in the working face,achieve safe mining under thick hard roofs,and provide a reference for rock burst prevention in working faces of mines with similar geological conditions.