Abstract:
Coal mine roadway adjacent to the goaf is subjected to superimposed stress and mining influence,increasing the risk of rockburst. This paper conducts a technical study based on the hydraulic fracturing in the return airway of the ZF1412 working face in Jiangjiahe Coal Mine. The research shows that during the mining period,the main roof undergoes “ O-X”type breakage,and the arc-shaped triangular roof area on the goaf-side is prone to forming a cantilever structure that does not easily collapse. In the sandstone layer 15 meters above the No. 4 coal seam in the return airway,three fracturing holes were arranged for fracturing experiments,determining the rock initiation pressure and the propagation patterns of primary and secondary fractures under hydraulic action. On-site monitoring results indicate that the support resistance of the support at the roadway end significantly decreased,with the support resistance of the No. 90 hydraulic support reduced by 12. 2 MPa compared to pre-fracturing levels. The effective horizontal radius of the fracturing was approximately 15 meters,and the fracture network formed an ellipsoidal shape,exhibiting axisymmetric distribution around the fracturing holes. Hydraulic fracturing effectively severed the connection between the working face and the goaf-side coal pillar,reduced the pressure on the goaf-side coal pillar,and prevented deformation of the return airway and potential rockburst hazards caused by excessive pressure on the protective coal pillar adjacent to the goaf during mining.