Grouting is a crucial technique for treating rock fractures in goafs

but it still faces challenges in predicting diffusion patterns and controlling the process; thus

optimization is needed to improve efficiency and effectiveness. As a case study

actual rock fractures in a grouting project for an underlying goaf in Jincheng City

Shanxi Province were used. A fracture model with controllable roughness was constructed

and transparent epoxy resin rough fractures were fabricated by 3D printing. And then

a self-developed visual experimental platform for rough fractures was established to analyze the diffusion characteristics

range

and grouting rate considering different grout concentrations

fracture roughness

grouting pressures and grouting rates

revealing the grouting diffusion mechanism with combination of grout concentration

fracture roughness

and grouting input conditions. And also

the phase interface theory was applied to characterize the diffusion pattern

and the fractal dimension was proposed to describe corresponding diffusion pattern under different conditions. The correlation between actual filling rate and filling capacity was explored

with “actual filling ratio” used as an index for grout filling capacity in rough fractures. These investigations show that grouting diffusion exhibits different patterns depending on grouting pressure

fracture roughness

and grout rheology

with grouting rate and grouting pressure as primary controlling factors and diffusion regulated by rheology and fracture morphology. Furthermore

faster grout diffusion leads to more irregular diffusion contours

which hinders complete filling of complex fracture networks

so the actual filling ratio can explain effective grouting in the fractures considering the combination of high-concentration grout and high grouting pressure. Additionally

a proposed numerical model for rock fracture grouting was established

verifying the reliability of the experimental results. The above achievements provide scientific supports for optimizing grout mixture design

grout hole spacing

and grouting pressure

solving corresponding parameter selection in traditional grouting methods for rock fractures grouting.