Rockburst prevention mechanism and engineering application of surface hydraulic fracturing in thick-hard roofs of deep mines in Yuheng mining area

WANG Chungang; WANG Wenzhong; BAI Junjie; LU Jianping; ZHOU Hao; LU Chuang

doi:10.11799/ce202510007

Abstract：Aiming at the large-scale fracture and instability of hard roof strata above coal seams in the deep mining areas of Inner Mongolia and Shaanxi,which leads to strong strata pressure behavior in working faces and,in severe cases,rockburst,we took the No.2202 working face of Balasu Coal Mine as the engineering background,and studied the mechanism and application of surface hydraulic fracturing for weakening thick-hard roof strata to prevent rockburst in deep mines of the Inner Mongolia-Shaanxi region using theoretical analysis and field measurements.The conclusions are as follows:Firstly,hydraulic fracturing creates a fissures network within the thick-hard strata,weakening their physical and mechanical properties and reducing the size of fractured blocks.This subsequently diminishes the energy accumulation capacity of the thick-hard strata and reduces dynamic loads during their breakage.Simultaneously,by increasing energy dissipation,it mitigates the impact of dynamic loads from above the fractured layer on the stress in the underlying coal seam.Secondly,under the premise of not damaging the original roadway support structure while weakening the energy accumulation capacity of thick-hard strata,the target fracturing layer and key parameters were comprehensively determined.Thirdly,the pressure-time and flow-time curves during hydraulic fracturing,along with water discharge observations in underground drainage boreholes,indicate that surface fracturing can generate fissures in the thick-hard strata,with good fracturing effectiveness.After fracturing,the total energy and frequency of microseismic events,the frequency of microseismic events with energy above 5000 J,the average weighting interval,and the average dynamic load coefficient were significantly reduced.The research results demonstrate that hydraulic fracturing can significantly attenuate strata pressure behavior in the working face,providing a reference for rockburst prevention in mines with similar geological conditions across the mining area.