A three-dimensional grouting model of slurry diffusion-particle deposition-permeability evolution in discrete fracture network

Abstract

Accurately characterizing slurry behavior in discrete fracture network remains challenging due to the complexity of fracture geometries, the deformability of apertures, and the nonlinear rheology of slurry. This study develops a novel three-dimensional grouting model that integrates slurry diffusion, particle deposition, and permeability evolution in discrete fracture network. The evolving composition of the slurry is described by the volume fractions of deposited (S) and suspended (C) particles. A spatial–temporal viscosity field is incorporated to capture the time-dependent changes in slurry properties as it diffuses along the flow paths. Moreover, fracture apertures deform dynamically under the influence of slurry pressure and particle deposition, establishing a bidirectional feedback mechanism between the flow field and fracture geometry. The accuracy of the numerical model is validated by comparing the predicted and experimental results of permeability evolution in both single fracture and fracture network. The results show that permeability decreases hysteresis arises from delayed particle deposition, while increased fracture intersections accelerate the transformation from suspended to deposited particles. Sensitivity analyses reveal that slurry diffusion is primarily governed by slurry properties such as grouting pressure and water–cement ratio, whereas deposition and sealing behavior are strongly influenced by fracture aperture and network density. Finally, the model facilitates the determination of optimal grouting duration under various conditions, offering a reliable reference for designing effective grouting strategies in complex fracture networks.