Hydraulic anisotropy of homogeneous soils and rocks: influence of the densification process

Estimation of hydraulic anisotropy of unconsolidated granular packs using finite element methods

“…pack C with regular grains and aspect ratio 1) and aspherical (e.g. packs A, B, E with irregular grains and aspect ratio 1) geometries are similar to values reported for sands and gravels at high porosity in [20]. However, the higher values observed for the ellipsoids and lenticular geometries (e.g.…”

“…Spherical and aspherical geometries with varying degree of heterogeneities are fairly isotropic; ellipsoidal (R = 2, 3) and lenticular geometries have decreasing anisotropy. Published data of clay [14] and sand [20] are also plotted.…”

“…Packings with the same degree of heterogeneity have higher anisotropy at higher aspect ratio. In the bedding plane of sedimentary rocks, the A r is usually lower than 1.5 which means that these rocks are nearly isotropic in that plane while it is usually lower than 4 for clay, with a few exceptions up to 42 [20]. Few results are available for granular materials, their A r is not always higher than 1.…”

“…Anisotropy ratio in transport properties of clay-bearing formations which exhibit grain shape alignments may be pronounced [14][15][16][17][18][19]. Also, homogeneous grains appear to be hydraulically isotropic at their highest void ratio and their anisotropy ratio increases when the density increases [20].…”

Discussion of "Network model for hydraulic conductivity of sand-bentonite mixtures"

“…Afterwards, it would be interesting to extend its use to predict the k value of any soil defined by its gradation and its limits of consistency. It would also be interesting to consider the effects of gravity and vertical static compaction to try to reproduce available data on permeability anisotropy of natural soils (e.g., Chapuis et al 1989b;Chapuis and Gill 1989).…”