PFC-based numerical simulation study on multiple influencing factors of fracture grouting in soil layers

Abstract

This study presents a numerical simulation of fracture grouting in soil layers using the discrete element software PFC. A numerical model with parameters matching those used in laboratory tests is first established and validated under different grouting pressures and depths. The simulated diffusion radii agree well with the experimental measurements in both trend and magnitude, confirming the reliability and applicability of the model. Subsequently, an orthogonal test scheme is designed to examine the effects of soil void ratio, grouting depth, and grouting pressure on grout diffusion morphology and the resulting diffusion radius. The results reveal that a larger void ratio facilitates permeation and gradually enlarges the diffusion radius, whereas a smaller void ratio leads to fracture-dominated diffusion with dendritic or vein-like patterns. Grouting depth exhibits a negative correlation with diffusion radius, as deeper burial increases confining pressure and raises the fracture initiation threshold, thus inhibiting grout propagation. Conversely, increasing grouting pressure enhances fracturing energy, accompanied by multiple radial main fractures and a significant increase in diffusion radius. These findings provide a theoretical basis for optimizing grouting parameters and improving reinforcement efficiency in soil layer engineering.