InterPore2022

Effects of compaction on pore structure and soil hydraulic properties

2 Jun 2022, 15:15

1h 10m

Poster Presentation (MS09) Pore-scale modelling Poster

Speaker

Mr Soheil Safari Anarkouli (Charles University)

Description

The hydraulic properties of porous media extensively depend on their pore structure as described by the size, arrangement, and connectivity of pores. The current work aims to provide a numerical simulation of the evolution of the pore size distribution (PSD) during oedometric compaction of Zbraslav sand. Apart from the derived unsaturated hydraulic properties, we will be particularly interested in predicting its saturated permeability with respect to non-Newtonian (shear-thinning) fluids.

In this study, we will follow the discrete approach during the sand compaction process introduced by Mahmoodlu et al. [1] and later studies. Discrete element method (DEM) can directly trace the motion of individual particles and explicitly consider the particle–particle interactions without the need of macroscopic constitutive correlations. We will use this method to generate a packing of idealized particles for a certain porosity and particle size distribution, and simulate the movement of grains during the compaction process. It is desirable to derive pore networks from the imaged DEM soil samples and thus establish the relationship between the particle geometric features and the pore characteristics. Subsequently, the extracted pore networks can be used as the input for prediction of hydraulic properties of soil [2].

Further step will be the simulation of the flow of various shear-thinning fluids through the media [3, 4]. We are particularly interested in how the observed variations in pore structure will be represented by the effective PSD obtained by the method introduced by Abou Najm et al. [5], i.e. computed from the observed permeabilities with respect to shear-thinning fluids. Based on this method, we will present the experimental measurement of the effective PSD directly during the oedometric test.

This research is supported by Czech Science Foundation under grant 21-27291S.

References

[1] Mahmoodlu, M. G., Raoof, A., Sweijen, T., & Van Genuchten, M. T. (2016). Effects of sand compaction and mixing on pore structure and the unsaturated soil hydraulic properties. Vadose Zone Journal, 15(8).

[2] Li, G. Y., Zhan, L. T., Hu, Z., & Chen, Y. M. (2021). Effects of particle gradation and geometry on the pore characteristics and water retention curves of granular soils: a combined DEM and PNM investigation. Granular Matter, 23(1), 1-16.

[3] de Castro, A. R., Agnaou, M., Ahmadi-Sénichault, A., & Omari, A. (2020). Numerical porosimetry: Evaluation and comparison of yield stress fluids method, mercury intrusion porosimetry and pore network modelling approaches. Computers & Chemical Engineering, 133, 106662.

[4] Hauswirth, S. C., Abou Najm, M. R., & Miller, C. T. (2019). Characterization of the pore structure of porous media using non‐Newtonian fluids. Water Resources Research, 55(8), 7182-7195.

[5] Abou Najm, M. R., & Atallah, N. M. (2016). Non-Newtonian fluids in action: Revisiting hydraulic conductivity and pore size distribution of porous media. Vadose Zone Journal, 15(9).