Numerical investigation on a grouting mechanism with slurry-rock coupling and shear displacement in a single rough fracture

A slurry diffusion model of a single random-roughness fissure is established to consider the slurry and geological fracture coupling based on the Navier-Stokes equation. The slurry flow characteristics and coupling response in a rough fracture are investigated. The influencing mechanism of roughness on the slurry flow was revealed. The calculation model of effective aperture is determined in a rough fracture. The shear displacement effects on the slurry flow are studied. The results show that this slurry diffusion model can more accurately reflect the grouting. A rougher fracture has a great effect on the flow because of the larger low-speed domains. The pressure gradient and maximum diffusion velocity increase parabolically with changes in the relative roughness. The conventional flat-panel model can cause an increasing deviation rate for determination of grouting parameters. The coupling degree distribution is temporal with spatial variations, and increases with the time-dependent viscosity, roughness (decreasing effective aperture), and a shortening path. The viscosity is the key controlling factor in grouting pressure. The roughness response after shear displacement is more significant, further revealing that on-site grout splitting often occurs at the narrow undulating tip with high viscosity and shear on a rough flow surface. The rough fracture model considering fluid-solid coupling is more consistent with the grouting phenomenon in engineering. And the roughness and shear are the key geological factors of grout splitting.