Cement-bentonite grout is widely employed for seepage control and dike reinforcement in hydraulic infrastructure projects. The time-varying viscosity of the slurry, the particle-size distribution, and the tortuosity of fluid flow path are important factors affecting the slurry diffusion in a spherical permeation grouting process. However, they are not fully considered in the current theoretical models. In this study, a theoretical spherical permeation grouting model for cement-bentonite slurry is established. Fractal theory is introduced to characterize the particle-size distribution and the tortuosity of fluid flow path. A series of experiments are performed to investigate the rheological properties of cement-bentonite slurry and validate the theoretical model proposed in this study. The impacts of grouting time, grouting pressure and bentonite content on the slurry diffusion process are examined through numerical simulation. The results show that the proposed model predicts slurry diffusion distance with an error of less than 3% under all tested conditions. Compared to models neglecting tortuosity or time-varying viscosity, the proposed model improves prediction accuracy by 20–30% and 8–10%, respectively. Numerical simulations further reveal that increasing bentonite content from 0% to 3% reduces diffusion radius by 71.2%, while doubling grouting pressure increases diffusion radius by up to 47.5%. This indicates that the proposed model can better describe the process of slurry permeation and provide valuable support for related grouting projects.
Gong et al. (Tue,) studied this question.