Clay tension zone and unsupported height
Why can a vertical excavation in clay sometimes remain standing while a similar excavation in sand collapses?
This article examines the concept of critical unsupported height, including:
The role of cohesion in soil strength
Rankine active earth pressure theory
Tension crack formation
The physical origin of the factor 4 in the equation:
Hc = 4c / (γ√Ka)
It also discusses why geotechnical engineers are often cautious about relying on cohesion for permanent designs, despite the surprisingly large unsupported heights predicted by theory.
A useful read for civil engineers, geotechnical engineers, engineering students, and anyone interested in slope stability and excavation behavior.
https://constructmagazine.com/critical-unsupported-height-in-clays/
u/constrobot — 12 days ago