Mechanics of the penetration and filtration of cement-based grout in porous media: New insights from CFD-DEM simulations

Cement permeation grouting is a standard ground improvement technique crucial for improving soil's me-chanical properties. This study applied the computational fluid dynamics and discrete element method (CFD-DEM) to investigate the penetration of cement-based grout in porous media and the filtration behaviours of the cement particles. A model of the interaction forces of cement particles from the literature is implemented and validated by comparing the simulation and experimental results. A series of simulations identified the different modes of penetration, the penetration-induced changes in pressure and the formation process of the filter cake. The size ratio of the available pore openings to the cement particle is critical among various factors that influence cement grouting because it determines the formation of a cement filter cake. The grouting pressures (from 100 kPa to 400 kPa) exert little effect on the penetration distance and cement distribution of the soil prone to filtration. The self-collapse of the retained particles was captured by visualising the filtration process to explain the filter cake's destruction. Furthermore, four typical retention morphologies were discussed from a microscopic perspective. This study provides new insights into the mechanics of the penetration and filtration of cement -based grout in porous media.

Automated summary

This study used computational fluid dynamics and discrete element method (CFD-DEM) to investigate the penetration and filtration behaviors of cement grout in porous media. The validity of a model for the interaction forces of cement particles was confirmed by comparing simulation and experimental results. The size ratio of pore openings to cement particles was found to be a critical factor influencing cement grouting, and grouting pressures had little effect on penetration distance and cement distribution in filtration-prone soil. This study provides new insights into the mechanics of cement grouting in porous media.