Permeability‐Anisotropy Due to Particle Shape

Abstract

Three facts can lead to permeability‐anisotropy in sedimentary soils: (1) Macro‐stratification; (2) micro‐stratification; and (3) flatness plus orientation of particles. The effect of flatness and orientation of particles is quantitatively investigated using a fabric of lenticular particles as a soil model. The investigations comprise permeability tests with alternate directions of percolation (i.e., parallel and perpendicular to the orientation of the particles) and theoretical considerations based on the hydraulic radius and pore channel model. The geo metrical parameters of the samples are measured with the help of oriented sec tions after stabilizing the model with hardening resin. The theoretical investi gations show that the factor of permeability‐anisotropy is equal to the square of the ratio of the pore‐channel‐tortuosity, and both the analytical and experi mental results reveal that, even for a high degree of particle‐flatness, the permeability‐anisotropy can hardly exceed a factor of about 2.5.