Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Stress characteristics

Evaluation Of The Method Of Stress Characteristics For Estimation Of The Soil Bearing Capacity

Mohammed Y. Fattah; Mohammed F. Aswad; Mohammed M. Mahmood

Engineering and Technology Journal, 2008, Volume 26, Issue 10, Pages 1171-1184

The classical bearing capacity theories rely on the superposition of three separate
bearing capacities – a technique that is inherently conservative – but they also rely on
tabulated or curve-fitted values of the bearing capacity factor, Nγ, which may be
unconservative. Further approximations are introduced if the footing is circular
(multiplicative shape factors are used to modify the plane strain values of , Nc, Nq and Nγ) or
if the soil is non-homogeneous (calculations must then be based on some representative
strength). By contrast, the method of stress characteristics constructs a numerical solution
from first principles, without resorting to superposition, shape factors or any other form of
In this paper, the validation of the method of stress characteristics is tested by solving
a wide range of bearing capacity problems. The results are compared with classical bearing
capacity theories; namely, Terzaghi, Myerhof, Hansen and Vesic methods.
It was concluded that the bearing capacity predicted by the method of stress
characteristics for the case of a circular footing in clay ranges between (3.7 – 4.0) greater than
Terzaghi, Meyerhof, and Vesic methods. This means that the method is not conservative for
this case and can be dependent for economic design of foundations. The bearing capacity
predicted by this method increases linearly with (D/B).
For all values of the angle of friction, φ, the method reveals bearing capacity values for
smooth footings greater than Terzaghi and Hansen and smaller than Meyerhof and Vesic
theories. Considering the foundation to be rough, the method gives bearing capacity values
greater than all other methods. The difference increases as the angle of internal friction
(φ) increases. This makes the method unreliable for rough foundations.