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发表于 2005-4-16 14:28:51
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来自 新加坡
Re:确定地基承载力
下面是摘自 Griffiths, D.V (1982) "Computation of bearing capacity factors using finite elements." Geotechnique 32, No. 3, 195-202
1. How to get the bearing pressure:?
In all cases the bearing pressure mobilized by a give vertical displacement was obtained by averaging the vertical stress component occuring in the first row of integrating points below the displacement nodes.
2. Why use displacement control rather than load control?
The rationale for using displacement rather than load control was based on numerical convenience and, to some extent, physical reality. Load control allows the applied stresses to be adjusted finely by the application of nodal forces, but implies a perfectly flexible foundation. Stress in excess of the bearing capacity are physically impossible, and failure of the numerical process is sginalled by a dramastic increase in the number of interations per load step, with correspondingly high computer times.
Under displacement control, which implies a perfectly rigid footing, equilibrium and yield can always be satisfied with relatively few iterations, even if failure has been reached. Failure under displacement control is indicated by a levelling out of the averaged stresses beneath the footing, which, having reached the bearing capacity, remain at that value despite further displacement increments. |
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