<p>The diffusion path and slurry viscosity play crucial roles in determining the diffusion range and reinforcement effect of permeation grouting. In this study, the tortuosity effect of the diffusion path and the rheological characteristics of the slurry are comprehensively considered, and a theoretical model for the spherical permeation grouting diffusion of Bingham - fluid slurries is established. The governing equations for the diffusion of rheological slurries are derived and experimentally verified. The results show that the injection pressure increases following an exponential function, initially rising slowly and then increasing rapidly as the diffusion radius expands. In the early stage of grouting, the slurry viscosity is relatively low, and both the injection pressure and the injection rate are the dominant factors controlling the slurry diffusion range. Once the slurry viscosity reaches a certain threshold, viscosity becomes the primary factor governing the diffusion range. Based on these findings, a grouting control strategy is proposed, which involves high - pressure and high - speed injection at the initial stage, followed by low - speed injection in the later stages. This strategy takes into account the formation conditions. In the early phase, a higher grouting pressure and rate are used to enable the slurry to diffuse rapidly within the fractured rock mass. Subsequently, the grouting rate is reduced to enhance the slow - penetration and compaction - diffusion effect into the surrounding rock. This control measure was applied to the repair and treatment of the fractured surrounding rock in the floor of the −1000 m haulage tunnel in the eastern section of Guqiao Mine, achieving favorable engineering effects.</p>