Study on parallel flow diffusion of granular slurry in porous media

Abstract

The migration velocity model and seepage pressure model of suspension grout with plane-parallel flow state in porous media were proposed based on mass conservation equation, seepage flow continuity equation, linear filtration law, and pressure gradient equations. The effect of the particle filtration process of suspension with distance on the migration velocity, pressure gradient, and seepage pressure was analysed. By using the independently developed monomer combined type osmotic grouting device, the diffusion velocity field and pressure field of cement slurry in sand layer were studied. Then, the value of model test was compared with the filtration theoretical values and without filtration theoretical values. Results show that the difference between the value of migration velocity with neglecting filtration effect and that of the model test was 1.2~17 times. With the decreased of K c/K 0, the theoretical value and the experimental value of filtration velocity decreased along the path, and the rate of both was positively correlated with the diffusion distance. At a certain diffusion distance, the model test value and the theoretical value of seepage pressure increase with time, but the rate was different. The difference between the model test value of seepage pressure and the theoretical value considering filtration was -23~84kPa, and the deviation rate was -70%~58%. The plane-parallel flow pressure model of slurry can accurately reflect the law of seepage field of cement slurry.

Theoretical Research on Diffusion Radius of Cement-Based Materials Considering the Pore Characteristics of Porous Media

“…Wang et al [ 6 ], taking Bingham slurry as the carrier, derived the analytical solution of slurry pressure attenuation and diffusion radius considering the tortuosity of the injected loose layer, and verified the rationality of the theory through field grouting. Xiao et al [ 7 ] and Han et al [ 8 ] deduced the slurry diffusion model considering the pore tortuosity effect based on the pore tortuosity effect combined with the power-law fluid constitutive equation, and analyzed the influence law of the tortuosity effect, slurry viscosity, rheological index, and grouting amount per unit time on the attenuation of slurry pressure in the direction of the diffusion radius. The results show that the fractal characteristics of porous media have a significant influence on the pressure attenuation and diffusion radius of slurry.…”