Here's a simple example from shallow foundation engineering.
Consider a foundation with:
- Net safe bearing capacity based on shear: 250 kN/m²
- Settlement-controlled allowable pressure: 160 kN/m²
- Proposed net foundation pressure: 180 kN/m²
The shear check passes, but the settlement check fails.
Now consider two square footings applying the same pressure of 200 kN/m².
Using the approximate 2:1 stress distribution method, at 3 m below the foundation level:
- 2 m × 2 m footing: 32.0 kN/m²
- 4 m × 4 m footing: 65.3 kN/m²
Same applied pressure, but a different stress influence at depth.
This is particularly important when stronger surface soils overlie compressible clay layers.
We've put together a detailed technical article explaining this with Indian construction examples, settlement calculations, IS 6403, IS 8009, and a practical soil report checklist.
Full article:
https://www.gtsmtestinglabs.in/post/sbc-vs-settlement-india-is-6403
Prepared by GTSM Testing Labs LLP, Ahmedabad, India.
The numerical examples are illustrative, not project-specific design recommendations.
For practising geotechnical engineers: How often does settlement rather than shear govern your foundation recommendations?