Diffusion Evolution Rules of Grouting Slurry in Mining-induced Cracks in Overlying Strata

In view of the problems of goaf water and harmful gas discharge in a coal mine, a new method of prevention and control is proposed in this paper, namely, mining fracture repair via slurry grouting. Research on the diffusion law of grout in rock strata to improve grouting theory and improve the grouting sealing effect is of great theoretical significance and engineering application value. The diffusion rules of grouting slurries under different working conditions are systematically explored and analyzed. The research results indicate that the slurry diffuses uniformly along the radial direction in the smooth crack in the smooth single crack grouting experiment. In addition, the faster the grouting speed is and the closer the distance from the grouting hole is, the greater the grout pressure and the greater the grout diffusion speed. Therefore, increasing the grouting speed moderately in grouting engineering practice can effectively accelerate the grouting process. The pressure of the grouting slurry at the measuring point at the same distance as the grouting hole is basically the same, which is also the main reason for the uniform diffusion of the slurry along the radial direction. The pressure decreases to the same level value when the slurry diffuses to a certain distance under different grouting speeds, which indicates that reducing the spacing of grouting holes can accelerate the grouting process more effectively than increasing the grouting speed.