A numerical study of plate anchors embedded in sand

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The work described in this thesis begins with an elastic analysis of ground anchors in which several assumptions were made. some of these assumptions limited the applicability of the analysis but some useful insights into the stress distribution around ground anchors were obtained. however, a more realistic non-linear analysis was required before any definitive conclusion could be drawn. finite element analysis appeared to be the most appropriate method. however, since the behaviour of sand is rather complex (dilatancy, softening) an appropriate stressstrain model was then necessary. after a review of several constitutive models for sands, vermeer's model which has the merit of being relatively simple yet comprehensive, has been studied ïin detail. however, this model does not describe softening behaviour since this is not a material property of a continuum. for this reason among others, it was decided that little advantage would be gained by implementing the model into the finite element program. instead, a simple linear elasticperfectly plastic model based on the mohr-coulomb yield criterion was employed in the finite element analyses. the effects of soil properties, embedment depth and initial stress conditions were studied as well as the effects of sand inhomogeneity and test scale. contours representing the stress distribution around the anchor and yield propagation during the loading history were plotted. this gave an insight into the progressive mechanism of failure occuring in the soil mass. the results from the finite element anlyses were based on the socalled k, failure load concept which appeared to give satisfactory results for loose sands.