Question

The ultimate bearing capacity of a sandy soil when tested with 750 mm diameter plate as determined from a field load test is 300 kN/sq.m. Estimate the ultimate bearing capacity (kN/sq.m) of a circular footing with a diameter of 1.5 m. 
1. 600
2. 150
3. 450
4. 750
5. 300

Answer 1

Correct Answer - Option 1 : 600

Concepts:

The ultimate bearing capacity in case of sandy soil is directly proportional to their width in case of strip footing or their diameter in case of Circular footing.

i.e.  q_u ∝ (B or D)

Note:

The ultimate bearing capacity in case of clayey soils is independent of the size of footing.

Calculation:

Given:  q_u = 300 kN/m² when diameter is equal to 0.75 m.

or

\({\left( {\frac{{{q_u}}}{B}} \right)_1} = \;{\left( {\frac{{{q_u}}}{B}} \right)_2}\)

Or

\({\left( {\frac{{300}}{{0.75}}} \right)_1} = \;{\left( {\frac{{{q_u}}}{{1.5}}} \right)_2}\)

⇒ q_u = 600 kN/m²