Example data table
Typical parameter sets. Load one, then press Calculate.
| Example | φ (deg) | c (kPa) | γ (kN/m³) | γsat (kN/m³) | B | L | Df | WTD | FS |
|---|---|---|---|---|---|---|---|---|---|
| Dense sand | 35 | 0 | 18 | 20 | 2 | 2 | 1.2 | 5 | 3 |
| Stiff clay | 0 | 75 | 19 | 20 | 2 | 2 | 1.0 | 3 | 3 |
| Loose sand | 28 | 0 | 17 | 19 | 1.5 | 2 | 0.9 | 2 | 3 |
Results
Unit: kPa
Nc
30.14
Nq
18.401
Nγ
23.502
q (overburden)
18
B′ (m)
2
L′ (m)
2
Shape factors
sc=1.3,
sq=1.2,
sγ=0.8
Depth factors
dc=1,
dq=1,
dγ=1
Ultimate (gross) qult: 735.894 kPa
Net ultimate qnet,ult: 717.894 kPa
Safe capacities (FS=3)
Gross safe qsafe,g: 245.298 kPa
Net safe qsafe,net: 239.298 kPa
Formula used
This tool applies a common shallow foundation formulation with optional shape and depth factors:
qult = c·Nc·sc·dc + q·Nq·sq·dq + 0.5·γeff·Nγ·sγ·dγ·B′
- q is overburden at base, using submerged unit weight if below water.
- B′, L′ are effective dimensions: B′=B−2ex, L′=L−2ey.
- N-factors from φ: Nq=eπtanφtan²(45°+φ/2), Nc=(Nq−1)/tanφ, Nγ by Vesic or Meyerhof.
- Shape factors: strip(1,1,1), square(1.3,1.2,0.8), circular(1.3,1.2,0.6), rectangular via B/L.
- Depth factors (optional): dq=1+2tanφ(1−sinφ)²(Df/B′), dc=dq, dγ=1.
How to use
- Choose unit system and method for Nγ.
- Enter φ, cohesion c, unit weights, and water table depth.
- Set footing geometry, depth, and eccentricities for effective sizes.
- Toggle depth factors if applicable to your design context.
- Press Calculate. Review ultimate and safe capacities.
- Export results as CSV or PDF for records and sharing.
Note: Always verify assumptions against relevant codes and project requirements.
Typical Soil Parameters (Reference)
Indicative values for preliminary studies. Replace with project-specific investigations.
| Soil | φ (deg) | c (kPa) | γ (kN/m³) | γsat (kN/m³) |
|---|---|---|---|---|
| Dense sand | 35 | 0 | 18 | 20 |
| Medium sand | 32 | 0 | 18 | 20 |
| Loose sand | 28 | 0 | 17 | 19 |
| Gravel | 40 | 0 | 20 | 21 |
| Stiff clay | 0 | 75 | 19 | 20 |
| Soft clay | 0 | 25 | 17 | 18 |
Bearing Capacity Factors vs φ (Selected)
Computed using the current method setting: Vesic.
| φ (deg) | Nc | Nq | Nγ |
|---|---|---|---|
| 0 | 5.7 | 1 | 0 |
| 25 | 20.721 | 10.662 | 10.148 |
| 30 | 30.14 | 18.401 | 23.502 |
| 35 | 46.124 | 33.296 | 55.729 |
| 40 | 75.313 | 64.195 | 140.536 |
Water Table Influence on Safe Capacity
Snapshot using current inputs and FS. Values show net safe capacity.
| Scenario | WTD (m) | qsafe,net (kPa) |
|---|---|---|
| At ground surface | 0 | 135.469 |
| Midway to base | 0.5 | 135.469 |
| At base level | 1 | 190.351 |
| Halfway into B′ below base | 2 | 214.824 |
| At Df+B′ (fully below) | 3 | 239.298 |
| Deep water table | 99 | 239.298 |