Ww. Harris et al., USE OF STEREOPHOTOGRAMMETRY TO ANALYZE THE DEVELOPMENT OF SHEAR BANDSIN SAND, ASTM geotechnical testing journal, 18(4), 1995, pp. 405-420
Experimental results are presented from plane-strain compression of a
fine-grained, water-saturated loose sand. Together with local measurem
ents of boundary stresses and deformations, systematic analysis of pho
tographs of the deforming specimen allowed for measuring deformations
and computing strain fields inside and outside the shear band. The pri
nciples, details, and accuracy of the procedure are described. The cap
abilities of stereophotogrammetry are illustrated through typical resu
lts obtained from undrained and drained tests. A gradual transition fr
om homogeneous deformation to temporary modes of localized strain to a
highly localized strain field is systematically observed. Prior to st
rain localization in the region where the final shear band eventually
forms, the soil contracts more than the rest of the specimen. As soon
as the final band is fully formed, the soil inside the band either rem
ains at constant volume or dilates. The nonuniformity of volumetric re
sponse throughout the specimen in globally undrained conditions implie
s there is water flow within the specimen.