Calculator
Enter site parameters and press Calculate. Results appear above this form.
Example data
Sample inputs and typical outputs (metric). Values are illustrative only.
| Support | H (m) | γ (kN/m³) | φ (°) | q (kPa) | c (kPa) | hw (m) | Ka | Approx. Mmax (kN·m/m) |
|---|---|---|---|---|---|---|---|---|
| Cantilever | 6 | 18 | 30 | 10 | 0 | 0 | 0.3333 | 52.0 |
| Anchored | 7 | 19 | 32 | 15 | 0 | 0 | 0.3073 | 41.5 |
| Cantilever | 5 | 17 | 28 | 0 | 5 | 0 | 0.3610 | 17.8 |
| Anchored | 6 | 18 | 35 | 12 | 0 | 4 | 0.2710 | 63.4 |
Formula used
Earth pressure
- Rankine active coefficient: Ka = tan²(45° − φ/2)
- Vertical stress: σv(z) = γ · z
- Active lateral pressure with surcharge: σh(z) = Ka(σv(z) + q)
- Optional cohesion reduction: σh(z) = Ka(σv(z) + q) − 2c√Ka
- Tension is not carried: pressures are clipped to zero when negative.
All pressures are per unit wall length. Use effective stresses when submerged soils apply.
Water and bending moment
- Hydrostatic pressure (simplified): pw(z) = γw · min(z, hw)
- Total pressure: p(z) = σh(z) + pw(z)
- Cantilever base moment (about dredge line): M = ∫ p(z)(H − z) dz
- Anchored option uses a simply supported beam between top and dredge line; reactions are found from statics, and M(z) is computed numerically.
Anchored walls commonly require free-earth or fixed-earth design. This calculator provides a fast comparison, not a code check.
How to use this calculator
- Select the unit system and support condition.
- Enter retained height, soil unit weight, and friction angle.
- Add surcharge and cohesion if your soil model requires them.
- If water applies, enable it and set the water depth.
- Press Calculate. Results appear above the form.
- Use Download CSV or Download PDF to save outputs.
Tip: For multi-layer soils, use representative averaged values for quick screening, then confirm with a detailed model.