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Micro-scale pore features in idealised granular materials
This paper presents a quantitative analysis to characterise the micro-scale geometric arrangement of pores in an idealised granular material. The long-term goal of the research is to investigate whether properties of the pore space can be linked to the complex mechanical response of granular soils observed in laboratory tests. Idealised assemblies of mono-disperse spherical particles have been observed in physical experiments using x-ray computed tomographic imaging and in numerical simulations using discrete element models. These assemblies cover a large range in void ratio within the amorphous regime of particle packing. The geometry and orientation of individual pores are defined within the continuous pore space using a tessellation that merges Delaunay simplexes based on the concept of maximal inscribed spheres between the particles. We show that the pore volume distribution is uniquely described by the analytical k-gamma distribution function proposed by Aste and Di Matteo (2008). Pore shape is related to the ratio of the pore volume to surface area. This can be defined analytically from the void ratio and number of edges forming the polyhedral pore unit cell. The pore orientation tensor is defined by directly incorporating the geometric information of the individual pores. This formulation of the orientation tensor can be applied at the micro-scale, allowing for the determination of microscopic anisotropy and preferred orientation of individual pores. It can also be applied at the macroscopic level, which revealed the isotropic pore configuration for the static assemblies of mono-disperse spheres considered in this study.Author(s):
Adnan Sufian
University of New South Wales
Australia
Adrian Russell
University of New South Wales
Australia
Mohammad Sadaatfar
Australian National University
Australia
Nicolas Francois
Australian National University
Australia
Andrew Whittle
Massachusetts Institute of Technology
United States