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COMPUTATION OF BEARING CAPACITY FACTOR Ng-PRANDTL'S
MECHANISM
D. M. Dewaikar and B. G. Mohapatra
ABSTRACT: In this paper, an analysis based
on Prandtl's failure mechanism is proposed for the evaluation
of bearing capacity factor, Ng,
using the limit equilibrium approach, coupled with Kotter's equation.
Except for shape of the failure surface, no other assumptions
are needed in the analysis. A methodology based on Kotter's equation
and force equilibrium conditions is developed to identify the
correct location of pole of the log spiral and hence the unique
failure surface. Using moment equilibrium condition, the point
of application of passive thrust is determined.
The proposed Ng values
are compared with other available theoretical predictions and
experimental results. They show a good agreement with some existing
theoretical results and also show a better agreement with available
experimental results.
The analysis shows that pole of the log spiral lies at the footing
edge for general shear failure conditions and the point of application
of the passive thrust is strongly influenced by angle of soil
internal friction.
Key words: bearing capacity, limit equilibrium,
passive thrust, point of application, pole of log spiral, shallow
foundation (ICC: E3)
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