A particle-scale analysis of unload-reload hysteresis for normally consolidated kaolin

The mechanical behaviour of sands and clays subject to normal (plastic) compression are very similar, albeit at different stress levels, despite the differences in inter-particle interactions (Hertzian normal contact forces or similar for sand) and electro-chemical forces for clays. However the hysteretic behaviour of clay is very different to sand with clays exhibiting springy hysteresis loops and ratchetting volumetric compaction. This paper aims to show that whereas the plastic compression arises from degradation of macro particles, the quasi-elastic unload-reload behaviour is consistent with an increase in the number of platelet edge contacts as clay stacks rearrange and compact.

Automated summary

The mechanical behavior of sands and clays under normal compression is similar despite the differences in inter-particle interactions. However, the hysteretic behavior of clay is very different, exhibiting springy hysteresis loops and ratchetting volumetric compaction.