Abstract
Grouting is a widely used method for sealing fractured rock masses around underground structures to reduce or stop groundwater inflow. One important aspect is the grout penetrability. So far, many experimental studies have been done to detect the penetrability of grout, which depends on the grout injection pressure, aperture of fracture from a borehole, distribution of cement particle and etc.However, the filtration and penetration mechanism of cement-based grout have not been clarified sufficiently yet due to complicated physical and chemical processes of grout, such as pressure-dehydration, consolidation, bleeding, clogging, absorption, sedimentation and condensation etc. To better understand the penetration and filtration mechanism of cement-based grout through rock fractures, a two-dimensional numerical model of coupled Computational Fluid Dynamics and the Distinct Element Method (CFD-DEM) had been developed. The fluid flow was simulated numerically by solving the Navier-Stokes equations using finite deference method. The calculated flow velocity field was used to the cement particle movement solved by DEM applying Newton's laws of motion. For the interaction between fluid and cement particle, immersed boundary method was used. By using a direct numerical simulation technique, the interaction between fluid and particles can be evaluated.In this study, the laboratory injection test (called“ short slot” experiment) performed in Royal Institute of Technology (KTH) in Sweden was simulated to verify the applicability of the newly developed CFD-DEM code. As a result, the simulation results agree qualitatively well with the actual experimental results, and the clogging process during the injection of cement-based grout was successfully reproduced by the CFD-DEM code. Moreover, based on these results, the influence of the particle size distribution of cement on the filtration and penetration behavior was discussed. The presented numerical model in this paper gives a better understanding for filtration and penetration mechanism of cement-based grout.
