Question

Four columns of a building are to be located within a plot size of $10\text{m}\times 10\text{m}$. The expected load on each column is $4000\text{kN}$. Allowable bearing capacity of soil deposit is $100{\text{kN/m}}^2$. The type of foundation best suited is

• A. Isolated footing
• B. Raft foundation
• C. Pile foundation
• D. Combined footing

Answer 1

The correct option is C Pile foundation

Total load to be sustained
$=4000\text{kN}\times 4$ columns

Total load $=16000\text{kN}$

Pressure (if load is uniformly sustained over the entire are)

$=16000{\text{kN/100m}}^2$

$=160{\text{kN/m}}^2$

The maximum bearing capacity is $100{\text{kN/m}}^2$ which is less than the pressure of $160{\text{kN/m}}^2$.
Thus, isolated footing and combined footing is not adequate.

If we adopt raft foundation the bearing capacity required will be $160{\text{kN/m}}^2$. Hence raft also not sufficient.

Thus we shall adopt pile foundation.