Ground Grouting Reinforcement Roof Technology for Coal Mining Under Direct Cover of Caving Belt

In order to solve the problem of strengthening the broken roof of the coal seam under the direct cover of the caving zone, taking the 7228 working face of Xutuan Coal Mine as the engineering background, the paper proposes the ground grouting reinforcement plan, and studies its construction technology from four aspects of slurry selection, grouting technology, ground drilling technology and grouting effect evaluation. The cement coal ash slurry proportioning schemes with water cement ratio of 1∶1 and solid phase ratio of 2∶8 have been determined through the slurry static test, slurry water separation test and slurry proportioning test; the secondary structure drilling and secondary tunneling scheme have been designed in the drilling technology to ensure the quality of drilling and make the slurry reach the target layer smoothly; the roof of coal seam 72 has been exposed through surface drilling, underground geophysical exploration and underground mining, and the grouting effect is verified. Through the ground grouting reinforcement, the strength and integrity of the 72 coal seam roof have been significantly strengthened, and the engineering geological problems faced by the 7228 working face are solved, and the high-efficiency mining of 7228 working face is realized.