How much should be the safe bearing capacity of soil?
Answers
Rocks (hard) without lamination and defects, for example granite, trap and diorite 3300 33
2 Laminated rocks, for example sand stone and lime stone in sound condition 1650 16.5
3 Residual deposits of shattered and broken bed rock and hard shale, cemented material 900 9
4 Soft rock 450 4.5
NON-COHESIVE SOILS
5 Gravel, sand and gravel mixture, compact and offering high resistance to penetration when excavated by tools. (Refer Note 5) 450 4.5
6 Coarse sand, compact and dry (with ground water level at a depth greater than width of foundation below the base of footing) 450 4.5
7 Medium sand, compact and dry 250 2.5
8 Fine sand, silt (dry lumps easily pulverized by fingers) 150 1.5
9 Loose gravel or sand gravel mixture; loose coarse to medium sand, dry (Refer Note 5) 250 2.5
10 Fine sand, loose and dry 100 1
COHESIVE SOILS
11 Soft shale, hard or stiff clay in deep bed, dry 450 4.5
12 Medium clay, readily indented with thumb nail 250 2.5
13 Moist clay and sand clay mixture which can be indented with strong thumb pressure 150 1.5
14 Soft clay indented with moderate thumb pressure 100 1.0
15 Very soft clay which can be penetrated several centimeters with the thumb 50 0.5
16 Black cotton soil or other shrinkable or expansive clay in dry condition (50 percent saturation) (Refer Note 2) To be determined after site investigation
17 Peat (Refer Note 2 & 3)
18 Fills or made up ground (Refer Note 4 & 5)