Permeation diffusion mechanism of pulse grouting with Bingham fluid considering tortuosity and spatiotemporal variations in viscosity

Abstract

Understanding the antiseepage and reinforcement mechanisms for pulse grouting remains inadequate at present compared with its engineering applications. To improve the theoretical framework of pulse grouting, a permeation diffusion model based on a Bingham fluid is developed, which incorporates the tortuosity of the slurry diffusion path and spatiotemporal variations in viscosity. The validity of the model is verified through a comparison of the theoretical predictions with the experimental results. The impacts of spatiotemporal viscosity variations and tortuosity on the slurry diffusion mechanism are evaluated via theoretical analysis. The permeation diffusion characteristics of pulse grouting and conventional methods are comparatively simulated and analysed via the COMSOL Multiphysics platform for secondary development. The results show that (i) the maximum relative discrepancy between the theoretical predictions and experimental measurements is less than 30 %, which can be further reduced to under 10 % with increasing grouting pressure, indicating that the theoretical model can offer valuable guidance for the design and implementation of pulse grouting projects. (ii) The spatiotemporal variations in slurry viscosity and the tortuosity of the diffusion path significantly affect permeation diffusion, which intensifies as the grouting pressure and duration increase. The theoretical diffusion distances without considering these two factors are 1.36 ∼ 1.74 times and 1.1 ∼ 1.32 times greater than the experimental results, respectively. (iii) The diffusion morphology of pulse grouting demonstrates a reduced range and a more uniform front under identical conditions, indicating that pulse grouting has significant advantages in the ability to control slurry diffusion compared with conventional methods.