Marine Pile Design Calculator
Compute ultimate and allowable bearing capacity for marine foundations on the seabed using the general bearing capacity equation with submerged soil conditions.
Inputs
Results
Ultimate bearing capacity (kPa)
910.9
Allowable bearing capacity (kPa)
364.4
Allowable total load (kN)
13,117.6
How to Use This Calculator
- Enter seabed soil parameters: undrained shear strength (kPa), friction angle (degrees), and submerged unit weight (kN/m3).
- Enter foundation width (m) and length (m).
- Read ultimate bearing capacity (kPa) from the Meyerhof or Hansen formula.
- Apply appropriate safety factors (typically 2.5-3.0) to get allowable bearing capacity.
- Verify pile tip resistance and skin friction contributions separately for pile design.
How the result changes with Friction angle φ (°)
| Friction angle φ (°) | Ultimate bearing capacity (kPa) | Allowable bearing capacity (kPa) | Allowable total load (kN) |
|---|---|---|---|
| 5 | 164.9 | 65.9 | 2,373.9 |
| 18 | 459 | 183.6 | 6,609.7 |
| 33 | 2,355 | 942 | 33,911.5 |
| 45 | 15,839.8 | 6,335.9 | 228,092.9 |
What each input means
- Undrained shear strength (kPa)
- Cohesion or undrained shear strength of the seabed soil.
- Friction angle φ (°)
- Internal friction angle of seabed soil. Clays ~0-5°, sands ~25-40°.
- Submerged unit weight (kN/m³)
- Buoyant unit weight of seabed soil (γ_sat - γ_water). Typically 7-10 kN/m³.
- Foundation width B (m)
- Width (shorter dimension) of the rectangular foundation.
- Foundation length L (m)
- Length (longer dimension) of the foundation.
- Embedment depth Df (m)
- Depth of foundation base below the seabed surface.
- Factor of safety
- Factor of safety applied to ultimate bearing capacity. Typically 2.0-3.0.
What each result means
- Ultimate bearing capacity (kPa)
- Maximum bearing pressure before failure.
- Allowable bearing capacity (kPa)
- Safe bearing pressure = q_ult / FoS.
- Allowable total load (kN)
- Maximum load the foundation can safely carry.
- Foundation area (m²)
- Footprint area of the rectangular foundation.
- Nc factor
- Bearing capacity factor for cohesion term.
- Nq factor
- Bearing capacity factor for overburden term.
- Nγ factor
- Bearing capacity factor for self-weight term.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersUndrained shear strength (kPa) = 20, Friction angle φ (°) = 25, Submerged unit weight (kN/m³) = 8, Foundation width B (m) = 6 = 7 input(s) provided
- Calculate Ultimate bearing capacityUltimate bearing capacity = cohesion * Nc * sc * dc +910.9 = 910.9
- Calculate Allowable bearing capacityAllowable bearing capacity = qUlt / safetyFactor364.4 = 364.4
- Calculate Allowable total loadAllowable total load = qAllow * foundationArea13117.6 = 13117.6
- Calculate Foundation areaFoundation area = foundationWidth * foundationLength36 = 36
- Calculate Nc factor20.72 = 20.72
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