CPT Soil Behaviour Type (SBTn)
The Soil Behaviour Type Normalized (SBTn) chart is used to classify soils based on cone penetration test (CPT) data. By plotting normalized cone resistance (Qtn) against normalized friction ratio (Fr), it identifies soil behaviour types such as sands, clays, and transitional materials.
Enter CPT data (Qtn and Fr) to classify soil behaviour.
⚠️ Results are indicative only — User should verify results independently.
Interpretation Guide
- 1:
- Sensitive, fine grained
- 2:
- Organic soils - clay
- 3:
- Clay - silty clay to clay
- 4:
- Silt mixtures - clayey silt to silty clay
- 5:
- Sand mixtures - silty sand to sandy silt
- 6:
- Sands - clean sand to silty sand
- 7:
- Gravelly sand to dense sand
- 8:
- Very stiff sand to clayey sand (heavily overconsolidated or cemented)
- 9:
- Very stiff fine grained (heavily overconsolidated or cemented)
- CCS:
- Clay-like-Contractive-Sensitive
- CC:
- Clay-like-Contractive
- CD:
- Clay-like-Dilative
- TC:
- Transitional-Contractive
- TD:
- Transitional-Dilative
- SC:
- Sand-like-Contractive
- SD:
- Sand-like-Dilative
Zones (Robertson, 2010)
Zones (Robertson, 2016)
References
- Robertson, P.K. (2010) – Soil Behaviour Type from CPT
- Robertson & Wride (1998) – Evaluating cyclic liquefaction potential