Abstract: To address grouting performance in water-rich sandy strata, a visualized grouting model test system and a discrete element numerical model for slurry diffusion were established. Comparative investigations were conducted to clarify the influence of grouting materials, grouting pressure, and groundwater level on the diffusion behavior of slurry, and to evaluate the water-blocking effectiveness of various grouting materials under seepage conditions. The results show that, under identical seepage conditions, the diffusion extent of the three grouting materials ranks as: two-component slurry > hydrophilic polyurethane > epoxy resin. The diffusion performance is positively correlated with slurry viscosity and fluidity. Grouting pressure is the primary controlling factor for slurry penetration depth, while groundwater level exhibits a negative correlation with grouting diffusion effectiveness. With increasing grouting pressure, the slurry diffusion radius exhibits a decelerating growth trend, with a significant reduction in growth rate when the pressure exceeds 0.3 MPa. Meanwhile, sand compaction increases concurrently, but weakens significantly along the radial direction.