Research on the advanced deep hole composite pre-grouting control technology for roof fracture zone of isolated face with large mining height

In order to solve the problem of coal wall and roof gangue in roof fracture zone of 15106 high mining isolated island working face in Sijiazhuang coal mine, based on the analysis of the reasons, the paper puts forward to reinforce the roof with deep hole retreating composite pre-grouting in advance of the return air chute.Through the numerical simulation software UDEC, the grouting parameters of groove advance pre-grouting are calculated.It is concluded that the grouting effect is best when the water cement ratio of grouting is 0.7∶1, the grouting pressure is 15 MPa and the grouting pressure of Malisan is 10 MPa.The support pressure of 15106 working face increases from 5 MPa to 25 MPa when it passes through the roof fracture zone, and the force is stable.The broken coal and rock mass in the roof fracture zone cements well, and the phenomenon of gangue and rolling no longer occurs, which reduces the loss time of strengthening the working face and ensures the safe and efficient advance of the working face.