vamseeachanta Geotechnical Engineering Skill
Offshore geotechnical analysis domain expertise for planning soil investigations, selecting foundation design methods, and sizing geotechnical elements (piles, anchors, mudmats, scour protection).
When to Use This Skill
- Planning a geotechnical analysis campaign
- Selecting bearing capacity or pile capacity methods
- Choosing anchor type for given soil and loading conditions
- Reviewing soil parameter derivation from CPT or borehole data
- Mapping standards coverage for geotechnical calculations
Soil Classification Systems
USCS (Unified Soil Classification System)
| Symbol | Description | Typical su (kPa) | Typical φ' (°) |
|---|---|---|---|
| CH | Fat clay | 20–200 | — |
| CL | Lean clay | 10–100 | — |
| ML | Silt | 5–50 | 25–30 |
| SM | Silty sand | — | 28–34 |
| SP | Poorly graded sand | — | 30–36 |
| SW | Well graded sand | — | 33–40 |
| GP | Poorly graded gravel | — | 35–42 |
Robertson CPT Classification (1990/2009)
| Zone | Ic Range | Soil Behaviour Type |
|---|---|---|
| 1 | — | Sensitive fine grained |
| 2 | > 3.60 | Organic soils / peat |
| 3 | 2.95–3.60 | Clays (clay to silty clay) |
| 4 | 2.60–2.95 | Silt mixtures |
| 5 | 2.05–2.60 | Sand mixtures |
| 6 | 1.31–2.05 | Sands (clean to silty) |
| 7 | < 1.31 | Gravelly sand to dense sand |
Method Selection Decision Tree
Bearing Capacity
Undrained (clay)?
├── Yes → Brinch Hansen general formula (DNV-RP-C212 Sec 5)
│ Nc = 5.14 for strip, shape/depth/inclination factors
└── No (sand) → Terzaghi/Meyerhof drained bearing capacity
Nq, Nγ from friction angle
Pile Capacity
Soil type?
├── Clay → Alpha method (API RP 2GEO Sec 6.4)
│ f = α × su; α from su/σ'v ratio
├── Sand → Beta method (API RP 2GEO Sec 6.5)
│ f = K × σ'v × tan(δ); K from Table 6.5.3-1
└── Layered → Sum unit shaft resistance per layer
Anchor Type Selection
| Soil Type | Load Direction | Recommended Anchor | Standard |
|---|---|---|---|
| Soft clay | Catenary | Drag (Stevpris/Vryhof) | DNVGL-RP-E301 |
| Soft clay | Vertical/taut | Suction caisson | DNV-RP-E303 |
| Stiff clay | Catenary | Drag (high capacity) | DNVGL-RP-E301 |
| Sand | Catenary | Drag anchor | DNVGL-RP-E301 |
| Any | Vertical (TLP) | Suction/driven pile | API RP 2GEO |
| Deep water | Taut leg | Torpedo/SEPLA | project-specific |
Typical Parameter Ranges
| Parameter | Symbol | Soft Clay | Stiff Clay | Sand |
|---|---|---|---|---|
| Undrained shear strength | su | 5–25 kPa | 50–250 kPa | — |
| Friction angle | φ' | — | — | 28–40° |
| Submerged unit weight | γ' | 4–7 kN/m³ | 7–10 kN/m³ | 8–11 kN/m³ |
| OCR | OCR | 1–3 | 3–20 | 1–5 |
| CPT cone factor | Nkt | 10–18 | 15–25 | — |
| su/σ'v (NC clay) | — | 0.20–0.30 | — | — |
Standard Reference Map
| Standard | Key Sections | Topic |
|---|---|---|
| API RP 2GEO | Sec 6 (piles), Sec 8 (foundations) | Pile + foundation design |
| DNV-RP-C212 | Sec 5 (bearing), Sec 6 (piles) | Soil mechanics |
| DNV-RP-E303 | Sec 4–7 | Suction anchor capacity |
| DNVGL-RP-E301 | Sec 3–5 | Drag/fluke anchor design |
| DNV-RP-F109 | Sec 3 | Pipeline on-bottom stability |
| DNV-RP-F107 | Sec 5 | Scour assessment |
| ISO 19901-4 | Sec 7–10 | Foundation design |
| API RP 2SK | Sec 6 | Mooring anchor requirements |
Module Import Paths
from digitalmodel.geotechnical.soil_models import SoilProfile, SoilLayer
from digitalmodel.geotechnical.piles import PileCapacityAnalysis
from digitalmodel.geotechnical.foundations import ShallowFoundation
from digitalmodel.geotechnical.anchors import AnchorCapacity
from digitalmodel.geotechnical.on_bottom_stability import OnBottomStability
from digitalmodel.geotechnical.scour import ScourPrediction
Related Skills
mooring-analysis— mooring system design consuming anchor capacitystructural-analysis— structural loads feeding foundation designmarine-offshore-engineering— general offshore engineering context
Version History
| Version | Date | Changes |
|---|---|---|
| 1.0.0 | 2026-02-26 | Initial skill — method selection, parameter ranges, standards map |