Correct Answer - Option 2 : Ultimate bearing power/Factor of safety
Explanation
Definitions of some key terms: -
1. Ultimate bearing capacity (qu):- It is the maximum pressure that the soil can support.
2. Net Ultimate bearing capacity (qnu):- It is the maximum pressure that the soil can support above its current overburden pressure.
\({q_{nu}} = {q_u} - \gamma D\)
3. Ultimate gross bearing capacity (qgross):- It is the sum of ultimate net bearing capacity and the overburden pressure above the footing base.
4. Net safe bearing capacity (qns): is the maximum net pressure intensity to which the soil at the base of the foundation can be subjected without risk of shear failure.
\({q_{ns}} = \frac{{{q_n}}}{{FOS}}\)
5. Safe bearing capacity (qsafe): - It is the working pressure that would ensure a margin of safety against the collapse of the structure from shear failure. The safe bearing capacity is usually a fraction of the ultimate net bearing capacity.
The relation between
\({q_{safe}} = \frac{{{q_{nu}}}}{{FS}} + \gamma D\)
Where,
Factor of safety (FS):- It is the ratio of ultimate net bearing capacity to the allowable net bearing capacity. In geotechnical engineering, it lies between 2 and 5
