Research on the Diffusion Law of Fire Extinguishment Slurry to Prevent Coal Spontaneous Combustion in Regenerated Roof.

Coal is a major part to stable energy structure. Borehole Grouting is a primary method used for the prevention and control of coal spontaneous combustion in the regenerated roof. However, the construction design of high-position grouting for the regenerated roof lacks a sufficient theoretical foundation due to the limited advancement in theoretical research on the high-position grouting of fracture. To fill the theory research gap of high-position grouting in regenerated roof, a fracture network high-position grouting numerical model was established. Based on the numerical model and assumptions of the equivalent path, a mathematical model of fracture network high-position grouting was established and a global sensitivity analysis was conducted. The results showed that the morphology of slurry diffusion is influenced by gravity and fracture orientation. The diffusion front undergoes three successive phases of transformation: hemispherical diffusion, curved diffusion, and plane diffusion. Based on the mathematical model, the fracture aperture has the largest first-order sensitivity and total-sensitivity index to grouting pressure during the whole phase of grouting. The second-order sensitivity index between fracture aperture and slurry viscosity, grouting pipe radius, grouting rate, dip, and azimuth is greater than other parameters. By focusing on key parameters and their interactions, this research contributes to enhancing the effectiveness of grouting construction while simultaneously reducing design complexity. [ABSTRACT FROM AUTHOR]