Safe Bearing Capacity of Soil
The capacity of the soil to allow the loads coming from the foundation is called the bearing capacity of the soil.
It is essential to know the bearing capacity of the soil before designing the foundation. Different field tests can determine it. However, standard safe bearing capacity values are available for different soil types, and these values can be assumed where test data is limited or speedy construction is required.
S.No | Type of Soil | Safe Bearing Capacity ( kN/m2) |
Cohesive Soils | ||
1. | Soft shale, hard or stiff clay in a deep bed, dry state | 440 |
2. | Medium clay readily indented with a thumbnail | 245 |
3. | Moist clay and Sand clay mixture, which can be indented by thumb pressure | 150 |
4. | Black cotton soil/expansive clay ( 50% saturated) in the dry state | 130 to 160 |
5. | Soft clay indented with moderate thumb pressure | 100 |
6. | Very soft clay which can be penetrated with the thump up to few centimeters | 50 |
Cohesionless Soil | ||
7. | Compact gravel/sand and gravel mixture with good resistance against penetration of tools | 440 |
8. | Compact and dry coarse sand | 440 |
9. | Compact and dry medium sand | 245 |
10. | Loose gravel or sandy gravel mixture, dry state | 245 |
11. | Fine sand and silt ( consists of dry lumps) | 150 |
12. | Loose and dry fine sand | 100 |
Rocks | ||
13. | Hard rocks such as granite trap, diorite, etc. | 3240 |
14. | Laminated rocks such as sandstone, limestone, etc. | 1620 |
15. | Residual deposits of shattered and broken bedrock and hard shale cemented material | 880 |
16. | Soft rocks | 440 |