A numerical solution of cavity expansion problem in sand based directly on experimental stress-strain curves

Abstract

A numerical solution of a spherical and cylindrical cavity expansion problem in sand is presented herein. The underlying theory is unbiased in that it is based directly on experimentally determined stress-strain curves. The solution makes it possible to follow the continuous variation of strains, stresses, and volume changes produced by cavity expansion. It essentially uses the "strain path" approach to determine the state of stress around the cavity, taking into account large strains and the effect of spherical stress variation on the mobilized shear resistance and the associated volume strains. A limited comparison with experimental data shows a reasonable agreement between theory and measurements.Résumé : Dans cette communication on présente une solution numérique du problème de l'expansion dans le sable d'une cavité de forme soit sphérique soit cylindrique. La théorie fondamentale est non biaisée, en utilisant comme base directement les courbes contraintes-déformations déterminées expérimentalement. La solution offre la possibilité de suivre la variation continue des contraintes et des déforamtions tant déviatoriques que volumiques autour de la cavité. Elle utilise essentiellement l'approche «cheminement de déformations» pour déterminer l'état de contraintes autour da la cavité, en tenant compte des grandes déformations et de l'effet de la variation de la contrainte sphérique sur la résistance au cisaillement mobilisée et sur les déformations volumiques associées. Une comparaison limitée avec les données expérimentales montre un accord raisonnable entre la théorie et les mesures.

Evidence for excess pore‐water pressure generated in subglacial sediment: Implications for clast ploughing

“…We select a value of M c at the lower end of this range because we expect that the effective pressure in the sediment is low as a result of generally high water pressures (locally exceeding ice-overburden pressure) in the hydraulically unconnected region of the glacier bed [e.g., Hubbard et al, 1995]. The value of L is taken between 0.3 and 0.6 m (10 -20 rod diameters) as determined by the cavity expansion theory [e.g., Ladanyi and Foriero, 1998]. Together with typical peak-to-peak velocity variations of $0.02 -0.03 m day À1 (Figure 3a) and hydraulic diffusivities for subglacial sediment ranging from 10 À7 to 10 À4 m 2 s À1 [Freeze and Cherry, 1979] in equations (3) and (2), we obtain amplitudes of excess pore-pressure variations immediately in front of the rod tip between 0.4 and 1.6 m.…”

Synthesis and investigation of intra-molecular charge transfer state properties of novel donor–acceptor–donor pyridine derivatives: the effects of temperature and environment on molecular configurations and the origin of delayed fluorescence

“…TICT/WICT excited-state formation is strongly favoured in polar solvents, 39 however, the nature of emitting species and their temperature dependencies are more complex in polar solvents. The specific solvent-solute interactions play a significant role in the nature of excited-state charge distribution, 40 in particular, the solvent molecules reorient themselves in the vicinity of solute molecules with decreasing temperatures, 41 and excited-state energy is transferred from the solute to solvent, so that the fluorescence peak exhibits a thermally-activated and solvent polarity assisted behaviour. 42 However, for potential use in optical devices, ICT emission has to be stabilised in the solid state.…”

Undrained cavity expansion in modified Cam clay II: Application to the interpretation of the piezocone test

“…This theory leads to a conclusion that at the cavity wall the shear strain is in®nite, when the cavity is expanded from zero radius (Collins & Yu, 1996). Ladanyi & Foriero (1998) have shown that, when the large strain assumption is followed throughout the development, it leads to the conclusion that the shear strain at the expanding cavity wall cannot exceed a value of ða2, or about 157%. This alternative result casts some doubt on the authors' conclusion that`the s u value interpreted directly from the corrected cone resistance will be 59% higher than the reference s u .…”

“…This de®nition results in in®nite shear strain when the radial strain is in®nite or when the cavity is expanded from zero radius. Ladanyi & Foriero (1998) reported that that the shear strain at the expanding cavity cannot exceed a value of ða2. This conclusion is believed to be applicable only to compression or extension of a long cylinder and thus is not applicable to the cavity expansion problem.…”