Abstract:
Addressing the challenges of strong mining-induced pressure manifestation in thick coal seam island working face and the resource loss caused by wide protective coal pillars, a coal pillar size calculation model was established based on the limit equilibrium theory. A high-strength anchoring system and a collaborative pressure relief technology combining "hydraulic fracturing and blasting" were proposed, implementing a three-dimensional pressure relief process that integrates hydraulic fracturing on the mining side and blasting pre-splitting on the gob side. The results indicate that, considering the movement characteristics of the near-field surrounding rock, the roadway along the gob can be arranged beneath the stable arc-shaped triangular rock mass formed after the roof fracture in the gob area. The measured plastic zone expansion range of the coal pillar is 3.5 m. The developed high-strength anchoring system enhances the anchoring depth, improves the constraint efficiency of the coal wall surface, and strengthens the shear resistance of the coal pillar. After the implementation of the collaborative pressure relief technology, the roadway floor heave decreased by 56%, and the lateral displacement rate of the coal pillar was reduced by 74%, effectively ensuring the service functionality of the roadway.