Discrepancy on Collapse Load
Discrepancy on Input Parameters
ANALYSIS TYPE: Drained.
KEY DIMENSIONS: Footing width 1m.
ADEQUACY FACTOR LOADING: Vertical load on footing (unit permanent load 1kN/m2).
BOUNDARY CONDITIONS: Surcharge = 0 kN/m2, symmetrical half space, footing base rough.
SOIL PROPERTIES: c'=0 kN/m2, phi' = 30 degrees, soil unit weight = 1 kN/m3.
PARTIAL FACTOR SET: Unity.
BENCHMARK SOLUTION: 7.377 (Ngamma/2 value)
REFERENCE: Smith, C.C. (2005) Complete limiting stress solutions for the bearing
capacity of strip footings on a Mohr-Coulomb soil. Geotechnique, 55 (8), October,
NOTES: Error on load = 26.9%. 'Benchmark' partial factor set with factor of 1.061
(i.e. 6.1%) on tan(phi)' is required to give benchmark solution. Corresponding value
of phi' is 28.5 degrees.
COMMENT: Result obtained using medium nodal density. This type of bearing capacity
problem involves a complex network of sliplines and requires a finer nodal spacing
to achieve a good solution. The Terzaghi bearing capacity formula using the EC7
recommended formula for N_gamma = 2*(Nq-1)*tan(phi) gives a solution of 10.05, an
error of 36.2%.