The infiltration of slurry in granular media plays an important role in face stability during slurry shield tunneling. This study investigates the effect of slurry viscosity in Fujian standard sand through a series of column tests combined with microstructural investigation, which remains unclear. The viscosity of slurry covers a wide range, from 1.8 to 2,248 mPa·s. Slurry particles in the low-viscosity test (1.8 mPa·s) fail to form an impermeable cake due to the loose stacking of slurry particles retained in sand voids, corresponding to a slight water pressure difference and relatively large permeability. For the high-viscosity test (2,248 mPa·s), an impermeable cake forms at a shallow depth; however, this internal cake is vulnerable to be disturbed and damaged due to its shallow thickness. Ultimately, one recommended viscosity, 56 mPa·s, is identified as a transition state with two-stage intact clogging, exhibiting an effective infiltration depth and intact internal cake that forms simultaneously. Experimental observations show a negative water pressure difference in the high-viscosity test, attributable to the siphonic principle. Furthermore, a measurement of slurry samples and solutes using the material observation apparatus could provide the microstructure evidence to interpret the effect of slurry viscosity in infiltration clogging. This study offers a reliable reference for interpreting the effect of viscosity on slurry clogging in infiltration performance.

The significance of pore size as a determinant in two-phase flow dynamics is widely acknowledged. However, the micro-scale behavior of flow including pore channel capillary and air-water interface development are not systematically interpreted due to the limitation of test and computation methodologies. In the present study, an investigation was conducted into the impact of varying pore throat widths on the flow of a two-phase fluid. For the investigation, numerical simulations were integrated with microfluidic experimentation to provide a comprehensive analysis. The results indicate that large pore diameters in porous media are associated with accelerated infiltration rates, leading to quicker stabilization. However, an inverse correlation exists between pore throat diameter and seepage area, with larger diameters yielding larger residual air areas. In this investigation, the “queuing effect” was observed across all tests, irrespective of pore throat diameter. Water initially permeated the central region of the pore network, sequentially inducing a breakthrough in adjacent pores. It was found that smaller pore throat diameters necessitated higher breakthrough pressures. Consistently, under unchanged inlet flow rates, narrower channels exhibited greater capillary resistance, impeding water flow. Specifically, for the four models with increasing pore throat widths, the critical capillary resistances are decreasing continuously from 87.6 to 38.2 Pa ultimately. Document Type: Original article Cited as: Lu, Z., Zeng, C., Zhang, Y., Lu, H. Study of the pore size influence on infiltration of porous media considering capillary effect. Capillarity, 2025, 14(1): 1-12. https://doi.org/10.46690/capi.2025.01.01 References Amiri, H. A., Hamouda, A. A. Evaluation of level set and phase field methods in modeling two phase flow with viscosity contrast through dual-permeability porous medium. International Journal of Multiphase Flow, 2023, 52: 22-34. Bachu, S. Review of CO2 storage efficiency in deep saline aquifers. International Journal of Greenhouse Gas Control, 2015, 40: 188-202. Badalassi, V. E., Ceniceros, H. D., Banerjee, S. Computation of multiphase systems with phase field models. Journal of Computational Physics, 2023, 190(2): 371-397. Beebe, D. J., Mensing, G. A., Walker, G. M. Physics and applications of microfluidics in biology. Annual review of biomedical engineering, 2002, 4(1): 261-286. Bhagat, A. A. S., Bow, H., Hou, H. W., et al. Microfluidics for cell separation. Medical & Biological Engineering & Computing, 2010, 48: 999-1014. Cai, J., Chen, Y., Liu, Y., et al. Capillary imbibition and flow of wetting liquid in irregular capillaries: A 100-year review. Advances in Colloid and Interface Science, 2022, 304: 102654. Cai, J., Jin, T., Kou, J., et al. Lucas-Washburn equation-based modeling of capillary-driven flow in porous systems. Langmuir, 2021, 37: 1623-1636. Cai, J., Perfect, E., Cheng, C. L., et al. Generalized modeling of spontaneous imbibition based on Hagen-Poiseuille f low in tortuous capillaries with variably shaped aper tures. Langmuir, 2014, 30(18): 5142-5151. Cao, S. C., Dai, S., Jung, J. Supercritical CO2 and brine displacement in geological carbon sequestration: Micro model and pore network simulation studies. International Journal of Greenhouse Gas Control, 2016, 44: 104-114. Celia, M. A., Reeves, P. C., Ferrand, L. A. Recent advances in pore scale models for multiphase flow in porous media. Reviews of Geophysics, 1995, 33: 1049-1057. Golparvar, A., Zhou, Y., Wu, K., et al. A comprehensive review of pore scale modeling methodologies for mul tiphase flow in porous media. Advances in Geo-Energy Research, 2018, 2(4): 418-440. Cottin, C., Bodiguel, H., Colin, A. Drainage in two dimensional porous media: From capillary fingering to viscous flow. Physical Review E, 2010, 82(4): 046315. Culligan, P. J., Barry, D. A., Parlange, J. Y., et al. Infiltration with controlled air escape. Water Resources Research, 2000, 36(3): 781-785. Gravesen, P., Branebjerg, J., Jensen, O. S. Microfluidics-a review. Journal of micromechanics and microengineering, 1993, 3(4): 168. Hirt, C. W., Nichols, B. D. Volume of fluid (VOF) method for the dynamics of free boundaries. Journal of Computational Physics, 1981, 39(1): 201-225. Hizir, F. E., Hardt, D. E. Effect of Substrate contact angle on ink transfer in flexographic printing. Paper Presented at Comsol Conference, Boston, USA, 7-9 October, 2014. Hu, R., Lan, T., Wei, G. J., et al. Phase diagram of quasi-static immiscible displacement in disordered porous media. Journal of Fluid Mechanics, 2019, 875: 448-475. Hu, R., Wan, J., Kim, Y., et al. Wettability impact on supercritical CO2 capillary trapping: Pore-scale visualization and quantification. Water Resources Research, 2017, 53(8): 6377-6394. Li, G., Zhan, L., Chen, Y., et al. Effects of flow rate and pore size variability on capillary barrier effects: A microfluidic investigation. Canadian Geotechnical Journal, 2022, 60(6): 902-916. Li, G., Zhan, L., Zhang, Z., et al. Pore network modeling of capillary barrier effects: Impact of pore sizes. Canadian Geotechnical Journal, 2023, 61(1): 174-182. Li, Q., Luo, K. H., Kang, Q. J., et al. Lattice Boltzmann methods for multiphase flow and phase-change heat transfer. Progress in Energy and Combustion Science, 2016, 52: 62-105. Mirjalili, S., Jain, S. S., Dodd, M. Interface-capturing methods for two-phase flows: An overview and recent develop ments. Center for Turbulence Research Annual Research Briefs, 2017, pp: 117-135. Morrow, N. R., Mason, G. Recovery of oil by spontaneous imbibition. Current Opinion in Colloid & Interface Science, 2001, 6(4): 321-337. Osher, S., Fedkiw, R. P. Level set methods: An overview and some recent results. Journal of Computational Physics, 2001, 169(2): 463-502. Patiño, I. D., Nieto-Londoño, C. Boundary element techniques for multiscale filling simulations in dual-scale fibrous reinforcements using two...

The two‐phase flow in porous media is affected by multiple factors. In the present study, a two‐dimensional numerical model of porous media was developed using the actual pore structure of the core sample. The phase field method was utilized to simulate the impact of displacement velocity, the water–gas viscosity ratio, and the density ratio on the flow behavior of two‐phase fluids in porous media. The effectiveness of displacement was evaluated by analyzing CO ₂ saturation levels. The results indicate that the saturation of CO ₂ in porous media increased as the displacement velocity increased. When the displacement velocity exceeded 0.01 m/s, there was a corresponding increase in CO ₂ saturation. Conversely, when the displacement velocity was below this threshold, the impact on CO ₂ saturation was minimal. An “inflection point,” M 3, was present in the viscosity ratio. When the viscosity of CO ₂ is less than 8.937 × 10 ⁻⁵ Pa·s (viscosity ratio below M 3), variations in the viscosity of CO ₂ had little impact on its saturation. Conversely, when the viscosity of CO ₂ exceeded 8.937 × 10 ⁻⁵ Pa·s (viscosity ratio greater than M 3), saturation increased with an increase in the viscosity ratio. In terms of the density ratio, the saturation of CO ₂ increased monotonically with an increase in the density ratio. Similarly, increasing density ratios resulted in a monotonic increase in CO ₂ saturation, though this trend was less pronounced in numerical simulations. Analysis results of displacement within dead‐end pores using pressure and velocity diagrams reveal eddy currents as contributing factors. Finally, the impact of pore throat structure on the formation of dominant channels was examined.

This study investigates the monotonic and cyclic performance of composite bucket foundation breakwater in clay through centrifuge modeling. The application of monotonic loads simulates extreme wave conditions, and cyclic load corresponds to long-term serviceability conditions. In centrifuge tests, three typical soil strengths were tested, and two load eccentricities were simulated to check the influence of wave force height. Multiple measurements were conducted, including rotation angle, horizontal displacement, vertical settlement, and pore pressure variation. When soil strength increases in monotonic centrifuge tests, the ultimate bearing capacity of the bucket foundation experiences significant growth, and the foundation failure pattern varies. In responding to the monotonic test, the foundation’s rotation center constantly moved downward during the loading process, indicating that the deeper soil would be activated to resist the horizontal loading. In contrast, the rotation center movement in the symmetric centrifuge test was opposed to the non-symmetric test because the deeper soil was required to provide resistance to balance the more severe load under the non-symmetric loading condition. It should be noted that non-symmetric loading does not impact the bucket foundation as seriously as symmetric loading. The utilization of deep-soil resistance in non-symmetric tests is beneficial in controlling deformation.