CFD-DEM simulations for injection of cement-based groutâ the effect of particle size

Grouting is a widely used method to seal and/or reduce permeability of fractured rock masses around underground structures. However, the filtration and penetration mechanism of cement-based grout have not been clarified sufficiently yet due to complicated physical and chemical processes of grouting. Therefore, the grout material and injection parameters such as injection pressure and Water/Cement ratio (W/C) are usually determined empirically by technical experts at the injection site. In this paper, for better understanding of the penetration and filtration mechanism of cement-based grout through rock fractures, the two-dimensional numerical model of coupled Computational Fluid Dynamics and the Distinct Element Method (CFD-DEM) was developed and the effect of particle size distribution and mean diameter of cement on the filtration and penetration mechanism was numerically investigated. The simulation results clearly shows that smaller and uniform particle size of cement will be preferable for the efficient and effective grouting.