Ground engineering · Consolidation & preloading
Consolidation settlement calculator
Primary settlement (NC or OC clay) and time to a degree of consolidation.
Standard: Terzaghi 1-D consolidation
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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 |
|---|---|---|
| Clay thickness | 5 | m |
| Initial void ratio e0 | 1.1 | |
| Compression index Cc | 0.35 | |
| Recompression index Cr | 0.05 | |
| σ'v0 at mid-layer | 60 | kPa |
| Stress increase Δσ | 50 | kPa |
| Clay state | Normally consolidated | |
| Pre-consolidation σ'p | 90 | kPa |
| cv | 2 | m²/yr |
| Target degree U (0–0.99) | 0.9 | |
| Drainage | Double (top & bottom) |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Primary settlement | 94 | mm |
| Drainage path Hdr | 2.50 | m |
| Tv at U | 0.848 | |
| Time to U | 2.65 | years |
| Settlement at U | 84 | mm |
- ✗ Settlement ≤ 25 mm (typical building limit)
Method, formulas and assumptions
- NC: s = Cc H/(1 + e0) log[(σ'0 + Δσ)/σ'0]
- OC: Cr up to σ'p, then Cc beyond
- Tv = (π/4)U² for U ≤ 0.6; Tv = 1.781 − 0.933 log[100(1 − U)] otherwise
- t = Tv Hdr² / cv
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.