Abstract: During the construction of slurry shield, a large amount of slurry is easy to permeate and filtrate, which leads to the instability of the excavation face. It is of great significance to maintain the stability of the excavation face that the slurry permeates and forms a membrane. Fully understanding the law of slurry permeation is the key to study the stability of the excavation face of slurry shield. Considering the filtration effect of soil skeleton on permeable slurry particles, a slurry concentration diffusion model is established, and the relationship between slurry concentration and stratum porosity is obtained. Based on the theory of porous media fluid mechanics, the slurry permeability parameters are solved, and the analytical model of slurry penetration-diffusion is established. The accuracy of this model is verified by indoor model test and comparison with existing theories. Finally, based on an engineering example, the temporal and spatial evolution law of slurry penetration-diffusion is analyzed, and the analytical results are consistent with the engineering understanding. The stratum porosity increases with the increase of slurry penetration distance, and then remains unchanged, and decreases gradually with the increase of slurry penetration time; the slurry penetration distance increases gradually with the increase of penetration time, and then tends to be stable. With the increase of penetration time and penetration distance, the slurry concentration, penetration velocity and seepage discharge decrease. The results show that the analytical model of slurry penetration-diffusion can reveal the law of slurry penetration-diffusion under different stratum parameters, and quantify the slurry permeability parameters, which has a good guiding role for the actual slurry shield construction.

Key words: slurry shield, slurry penetration, analytical model, spatial-temporal evolution mechanism