Limit analysis of reinforced embankments on soft soil

© 2016 Elsevier Ltd.Previous research into the stability of reinforced embankments founded on soft soil has presented limited studies based on a narrow range of assumed failure mechanisms. In this paper comprehensive parametric studies of reinforced and unreinforced embankments were conducted using the general purpose computational limit analysis approach Discontinuity layout optimisation (DLO). Comparisons with previous Limit Equilibrium and FE results in the literature showed good agreement, with the DLO analysis generally able to determine more critical failure mechanisms. Simplified, summary design envelopes are presented that allow critical heights and reinforcement strengths to be rapidly determined based on soft soil strength and depth, and show how the balance between soft soil strength and reinforcement strength combines to affect overall stability

Sinus histiocytosis with massive lymphadenopathy

Two cases of a recently described entity, 'sinus histiocytosis with massive lymphadenopathy,' occurring in Black males, are reported. Prominent cervical adenopathy was the main presenting feature in both. Histologically, these nodes were characterised by pronounced proliferation of sinus histiocytes which showed phagocytosis of blood cells, predominantly Iymphocytes. One of the patients has been followed up for 9 years and has remained clinically well despite persistence of the adenopathy. The importance of recognition of this condition is stressed in order to obviate unnecessarily radical therapy for a mistaken diagnosis of malignancy.S. Afr. Med. J., 48, 451 (1974)

Operator-Algebraic Approach to the Yrast Spectrum of Weakly Interacting Trapped Bosons

We present an operator-algebraic approach to deriving the low-lying quasi-degenerate spectrum of weakly interacting trapped N bosons with total angular momentum \hbar L for the case of small L/N, demonstrating that the lowest-lying excitation spectrum is given by 27 g n_3(n_3-1)/34, where g is the strength of the repulsive contact interaction and n_3 the number of excited octupole quanta. Our method provides constraints for these quasi-degenerate many-body states and gives higher excitation energies that depend linearly on N.Comment: 7 pages, one figur

Upper bound limit analysis of soils with a non-linear failure criterion

Limit analysis is a widely used technique for the analysis of geotechnical collapse states and there exists a significant body of literature covering its application to soils with a linear failure criterion. However, such a failure criterion is often an idealisation of an actual non-linear response for which available analytical techniques are limited. This paper presents a new fully general solution procedure for generating upper bound multi-wedge rigid block mechanisms for a soil with a non-linear failure criterion, utilising a curved interface that obeys the non-linear yield function flow rule along its full length. This work extends the long established kinematic sliding wedge approach for linear soils and is illustrated through application to active and passive retaining wall and anchor/trapdoor problems. Through additional consideration of the lower bound solution, close bounds on the retaining wall problem to within ~1% are established. The ability of the non-linear upper bound solution to predict the shear and normal stress at every point along the failure surface is discussed