Sr. No. | Types of Rocks and Soils | Maximum safe Bearing capacity tonnes/m2 |
1. | I. Rocks Rocks-hard without laination and defects, for example, granite and trap. | 330 |
2. | Laminater rocks (for example, sandstone and limestone) in sound condition. | 165 |
3. | Residual deposits of shattered and broken bed rock and hard shale, cemented material. | 90 |
4. | Soft rock | 45 |
5. | II. Non-cohesive Soils Grave, sand and gravel compact and offering high resistance to penetration when excavated by tools | 45 |
6. | Coarse sand, compact and dry. | 45 |
7. | Medium sand, compact and dry. | 25 |
8. | Fine sand, silt (dry lumps easily pulnerised by the fingers) | 15 |
9. | Loose gravel or sand gravel mixture; loose coarse to medium sand, dry. | 25 |
10. | Fine sand, loose and dry. | 10 |
11. | III. Cohesive Soils Soft shale, hard or stiff clay in deep bed, dry. | 45 |
12. | Medium clay, readily indented with a thumb nail. | 25 |
13. | Moist clay and sand clay and mixture which can be incented with strong thumb pressure. | 15 |
14. | Very soft clay which can be penetrated several centimetres with the thumb. | 5 |
15. | Black cotton soil or other shrinkable or expensive clay in day condition (50 per cent saturation). | 15 |
- Compactness or looseness of non-cohesive materials may be determined by driving a wooden picket of dimensions 5x5x70 cm. With a sharp point. The picket shall be pushed vertical into the soil by the full weight of a person weighing at least 70 kg. If the penetration of the picket exceeds 20 cm., the loose soil shall be assumed to exist.
- Peat may occur in a very soft spongy conditions or may be quite firm and compact.
- The strength of made-up ground depends on the nature of the material, its depth and age, and the methods used by consolidating it.
