Experimental research on "drilling-cutting-fracturing" pre-fracturing to prevent rock burst technology for deep hole of roof of coal seam

Abstract:In view of problems of complicated process of slot prefabrication and poor quality of seam formation in existing roof directional hydraulic fracturing technology, a technology of drilling, high-pressure water jet cutting and high-pressure hydraulic fracturing (drilling-cutting-fracturing) integrated pre-fracture roof to prevent rock burst was put forward, and experimental research of the technology in Hulusu Coal Mine was carried out. The experimental results show that the "drilling-cutting-fracturing" integrated technology and equipment can cut grooves manually without retreating drill pipe, and use single hole retreating multiple fracturing to improve construction efficiency. The symmetrical double hole high pressure jet device can effectively form a 4-5 mm wide artificial fracture groove to increase fracture cutting effect, reduce fracture initiation pressure,and expand fracture radius. The maximum single fracturing radius of roof strata with uniaxial compressive strength of 50-60 MPa can reach 15 m. The "drilling-cutting-facturing" technology weakens the roof and reduces the stress level of surrounding rock. The number of high-energy microseismic events near the goaf roadway has been greatly reduced, and the frequency and energy of microseismic events have not changed dramatically, so as to ensure the smooth mining of the working face.