Site investigation · In-situ testing
Plate load test calculator
Pressure–settlement curve to deformation modulus and modulus of subgrade reaction.
Standard: AS 1289.6.5.1 style · Ev (DIN 18134 form) · Boussinesq rigid plate
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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 |
|---|---|---|
| Plate diameter | 300 | mm |
| Poisson's ratio ν | 0.3 | |
| Pressure (kPa), settlement (mm) | 0, 0 50, 0.45 100, 0.95 150, 1.50 200, 2.10 250, 2.80 300, 3.60 350, 4.55 |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Ev (0.3–0.7 pmax) | 18.3 | MPa |
| Elastic E (rigid plate) | 17.4 | MPa |
| k at 1.25 mm | 102 | kPa/mm (MN/m³) |
| Range used | 105–245 | kPa |
- ✓ Curve reaches 1.25 mm settlement
Method, formulas and assumptions
- Ev = 1.5·r·Δσ/Δs over 0.3–0.7 of the maximum pressure
- E = π/4 · D(1 − ν²) · Δσ/Δs (rigid circular plate on elastic half-space)
- k = p / s at s = 1.25 mm; scale to footing size before use
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.