[Solved] Ultimate bearing capacity of soil defined as (2024)

Explanation:

Definitions of some key terms:

1. Ultimate bearing capacity of the soil (qu):

It is themaximumgross pressure at thebase of the foundationwhich can be applied without shear failureorit is theminimumgross pressure at which soil justfails in shear.

2. Net ultimate bearing capacity (qnu­):

It is the maximum net pressure at the base of the foundation which can be applied without shear failure or it is the minimum net pressure at which soil just fails in shear.

\({q_{nu}} = {q_u} - \gamma D\)

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):

It 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

As it is asked in Decreasing Order (i.e.) High to Low

Ultimate bearing capacity > Net ultimate bearing capacity > Gross Safe bearing capacity > Net safe bearing capacity