Optimal displacement mechanisms beneath shallow foundations on linear-elastic perfectly plastic soil

• Published in: Géotechnique 2013-12, Vol.63 (16), p.1447-1450
• Main Authors: MCMAHON, B. T, HAIGH, S. K, BOLTON, M. D
• Format: Article
• Language: English
• Subjects: Displacement; Earth sciences; Earth, ocean, space; Energy methods; Engineering and environment geology. Geothermics; Engineering geology; Exact sciences and technology; Finite element method; Mathematical analysis; Optimization; Rigidity; Settlements; Soil (material)
• ISSN: 0016-8505; 1751-7656
• DOI: 10.1680/geot.13.T.002

An energy method for a linear-elastic perfectly plastic method utilising the von Mises yield criterion with associated flow developed in 2013 by McMahon and co-workers is used, to compare the ellipsoidal cavity-expansion mechanism, from the same work, and the displacement fields of other research by Levin, in 1995, and Osman and Bolton, in 2005, which utilise the Hill and Prandtl mechanisms, respectively. The energy method was also used with a mechanism produced by performing a linear-elastic finite-element analysis in Abaqus. At small values of settlement and soil rigidity the elastic mechanism provides the lowest upper-bound solution, and matches well with finite-element analysis results published in the literature. At typical footing working loads and settlements the cavityexpansion mechanism produces a more optimal solution than the displacement fields within the Hill and Prandtl mechanisms, and also matches well with the published finite-element analysis results in this range. Beyond these loads, at greater footing settlements, or soil rigidity, the Prandtl mechanism is shown to be the most appropriate.