2.ii. Force chains

Beads arc (1’16)

In this video, we observe the resistance of the frictional forces at work, which make it possible to form arcs strong enough to support the weight of the beads above.

Photoelastic grains (1’40)

In this video, we observe the transmission of forces applied to the top of a pile of irregular grains in 2D. Through a few points of contact, the forces form “chains” that tend to go sideways. A particularity wich explain why

This observation explains why the formwork used for the adobe must be strongly reinforced. This also explains why a maximum thickness must be respected per layer of loose soil for an optimal compaction.

Watch this video extract, from 6’05 to 7’45

The vibrations and compaction forces of the pneumatic rammers are partially taken up by the reinforced formwork.

Mini Exercise

The next quiz is an exercise. It does not count for any learning assessment.