Abstract
Roof management in coal mines is a critical technology challenge to realize safe production. Dynamic disasters can be induced by a sudden collapse of the roof when encountering a thick hard roof above a coal seam. To solve this problem, directional hydraulic fracturing technology was utilized in the coal mine WP with a thick hard limestone roof. To effectively cut artificial transverse grooves in a fracturing hole in rock with a high strength, the KZ54-type transverse grooving bit was developed. Furthermore, the developed small-aperture high-pressure span-type expansion sealer can effectively seal the holes and ensure hydraulic crack expansion. The field observations show that the radii of extension of the hydraulic fractures were 15–20 m and that the rupture pressure at various depths in the holes ranged from 9 to 32 MPa from the orifice to the bottom of the hole. The deeper the fracturing location in the hole, the higher the fracturing pressure was. The principal stresses in front of the working face and the resistance forces of the hydraulic supports at the working face were monitored when the working face advanced. The first weighting of the roof decreased from 38.3 to 26 m, and the periodic weighting decreased from 26 to 13.7 m. Hydraulic fracturing reduced the resistance force of the supports at the working face.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
