Foundations · Footing settlement
Footing settlement & stress distribution calculator
Immediate settlement of a rectangular footing plus consolidation of a clay layer, with the vertical stress increase compared by Boussinesq and 2:1.
Standard: Boussinesq (Newmark corner) vs 2:1 · elastic + 1D consolidation
Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Footing width B | 2.5 | m |
| Footing length L | 3 | m |
| Gross bearing pressure q | 180 | kPa |
| Founding depth Df | 1 | m |
| γ (above water) | 18 | kN/m³ |
| γsat | 19.5 | kN/m³ |
| Water table depth | 2 | m |
| Soil modulus Es (for immediate) | 25 | MPa |
| ν | 0.3 | |
| Rigidity factor (1 flexible centre, 0.8 rigid) | 0.8 | |
| Depth from footing base to top of clay | 2 | m |
| Clay thickness | 4 | m |
| Cc | 0.35 | |
| Cr | 0.05 | |
| e0 | 1.1 | |
| OCR | 1.5 | |
| Allowable total settlement | 40 | mm |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Net pressure qn | 162 | kPa |
| Immediate settlement | 14.5 | mm |
| Δσ at clay mid-depth: Boussinesq | 30.2 | kPa |
| Δσ at clay mid-depth: 2:1 | 26.7 | kPa |
| σ′v0 / σ′p at clay mid-depth | 65 / 98 | kPa |
| Consolidation settlement | 15.8 | mm |
| Total | 30.2 | mm |
- ✓ Total ≤ 40 mm
Method, formulas and assumptions
- Immediate: s = qn·(B/2)(1 − ν²)/Es · 4·Ic(L/B) × rigidity factor (Steinbrenner corner factor, half-space)
- Boussinesq centre: Δσ = 4·qn·I(B/2z, L/2z) (Newmark 1935)
- 2:1: Δσ = qn·BL/[(B + z)(L + z)]
- Clay: s = Cr·H/(1+e0)·log(σ′p/σ′0) + Cc·H/(1+e0)·log(σ′f/σ′p) (single layer, mid-depth)
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.