Bifurcation and shear band propagation in sands

Abstract

Under simple or combined stresses, homogeneous sand specimens exhibit localization of deformation followed by shear band formation. This phenomenon has been extensively studied under plane strain loading conditions. This paper studies the initiation and propagation of the shear bands that develop in thin long hollow cylinders of sand subjected to a combination of axial torsional and spherical stresses. Digital image processing techniques are used to observe and measure the displacements and the initiation and development of the shear bands. The effects of the inclination of the principal stresses on the axis of symmetry, the relative density, the con®ning pressure and granulometry are examined. Strain measurements within the shear bands open the door to a more complete description of the mechanical behaviour of the material, in particular beyond the peak, in the so-called strain softening zone.

Energy dissipation and post‐bifurcation behaviour of granular soils

“…limiting values of the friction angle f and dilatancy angle c. The first solution is the classical Coulomb solution, whereas the second one is the Roscoe [57] solution. The third solution was first proposed by Arthur et al [8] on the basis of experimental observations, was subsequently proven theoretically within the framework of shear-band bifurcation analysis [10], and was supported experimentally by Vardoulakis [10] and Saada et al [58].…”

Non-coaxiality of strain increment and stress directions in cross-anisotropic sand

“…http://dx.doi.org/10.1016/j.ijsolstr.2013.12.003 rotation of principal stress axes in physical space (e.g. Lade 1975Lade , 1976Hight et al, 1983;Ishihara and Towhata, 1983;Tatsuoka et al, 1986;Symes et al, 1984Symes et al, , 1988Pradhan et al, 1988;Vaid et al, 1990;Vaid and Sayao, 1995;Saada et al, 1999;Zdravkovic and Jardine, 2000;Sivathayalan and Vaid, 2002;Chaudhary and Kuwano, 2003;Yang et al, 2007;Lade et al, 2008Lade et al, , 2009. Similar testing and analyses have also been performed on clay (e.g.…”

Grain-scale processes governing shear band initiation and evolution in sands

“…With regard to shear band onset, under plane strain conditions, shear banding has been most commonly observed to initiate during hardening (Desrues et al, 1985;Han and Vardoulakis, 1991;Finno et al, 1997;Desrues and Viggiani, 2004); however, Alshibli et al (2003) reported no evidence of shear banding prior to peak stress, and Vardoulakis et al (1978) observed shear banding and peak stress to directly coincide. Shear bands have been observed to form during hardening in hollow cylinder tests (Saada et al, 1999), and in true triaxial tests over a wide range of three-dimensional stress conditions . Under conventional triaxial compression conditions, shear banding most often has been observed to form during softening (Lade, 2002;Alshibli et al, 2003).…”

“…For example, even amidst the use of advanced sensing techniques, often the onset of shear banding has been detected merely according to some correlation with global strain response (e.g. Vardoulakis and Graf, 1985;Han and Vardoulakis, 1991;Finno et al, 1997;Saada et al, 1999;Wang and Lade, 2001). Shear banding in sands is a local phenomenon, with thicknesses on the scale of around 10-20 grain diameters (e.g.…”