Analysis of the diffusion range of the sleeve valve pipe permeation grouting column-hemispheric under the variation of the permeability of porous media

Grouting is widely used to solve problems such as water inrush and collapse in tunnels and subways, with permeation grouting being the most common method. This study explores the influence of fluid flow resistance on the permeability of porous media and derives an analytic expression for the variation of permeability in porous media based on the diffusion law of cement-based grout columns-hemispherical diffusion. Based on this, a Newtonian fluid permeation grouting column-hemispherical diffusion model considering the variation of permeability in porous media is established, combining the rheological equation and the equilibrium equation of the Newtonian fluid. The theoretical results considering the influence of fluid flow resistance on the permeability of porous media are consistent with the results of existing laboratory tests and numerical simulations, which are closer to the experimental results, thus verifying the effectiveness of the proposed theoretical mechanism. Parameter analysis shows that with the increase of grouting pressure and grouting time, the diffusion radius of the Newtonian fluid infiltration grouting, considering the variation of permeability in porous media, increases rapidly and then increases slowly, and with the increase of porous media porosity, its radius decreases gradually. The research results can provide theoretical support for selecting grouting parameters and quality control in porous media infiltration grouting engineering practice.