An investigation on the strength anisotropy of compacted clays

This paper reports some results of an experimental investigation on the strength anisotropy of a compacted clayey soil typical of those used as impermeable cores of earth dams. Large cubic samples of the selected soil were first prepared using various compaction levels. Cylindrical specimens were then taken from the block samples both along and perpendicular to the compacting direction. The strength anisotropy was evaluated by carrying out unconfined compression tests. The influence of compaction moisture content and dry density on the strength anisotropy was also investigated. The strength anisotropy was observed in all specimens i.e. the unconfined strength in the compacting direction was larger than that in lateral direction. The strength anisotropy ratio varied from about 1.04 to 1.23 depending on the soil state parameters.

Research Highlights
► Compacted clay samples were prepared both along and perpendicular to the compacting direction.
► Unconfined strength in the compacting direction was larger than that in lateral direction.
► Greater anisotropy was observed with greater dry densities and higher compacting moistures.
► Saturating the compacted samples decreased their strength, while overall anisotropy increased.
► It was suggested compacting clayey cores at moistures >OMC and high compaction ratios.