Numerical Studies of Bearing-Capacity Factor Nγ
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Volume 123, Issue 1
Abstract
Plane-strain, finite-element, and finite-difference computations of the bearing-capacity factor, Nγ, have been made for smooth and rough footings, for friction angles, ϕ, in the 30°–45° range, and dilation angles, ψ, in the 0 ≤ψ≤ϕ range. The finite-element analyses were based on a tangent stiffness approach. The commercially available code, fast Lagrangian analysis of continua (FLAC), was used for the finite-difference analyses. It was found that these methods may be used to obtain reliable Nγ values provided they are used cautiously. To obtain high-quality solutions, however, it is necessary to review the results critically, and, if necessary, alter the control parameters (e.g., mesh dimensions, number of calculation increments) being used. Computational difficulties were found to increase with increasing ϕ, and with increasing difference between ϕ and ψ, and the significant of these difficulties with regard to the use of the two computational techniques is discussed here. Curves relating Nγ to ϕ are presented, and compared to previously published relations. It is shown that commonly used values of Nγ, which have generally been based on associated plasticity calculations, are unconservative for real soils, for which ψ<ϕ.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 123 • Issue 1 • January 1997
Pages: 20 - 29
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Copyright © 1997 American Society of Civil Engineers.
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Published online: Jan 1, 1997
Published in print: Jan 1997
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