Yielding of Sand in Plane Strain

Abstract

A flow rule has been presented for sand yielding during shear loading, and has been used to predict certain features of plane strain tests reported in the literature. The flow rule expresses quantitatively the departure from normality commonly observed in shear tests on sand, and shows that this departure is a function only of the true angle of friction of the particles. Associating failure surfaces with velocity, rather than stress characteristics, the flow rule is used to predict the inclination of these surfaces. On the basis of the angle to be expected between stress and velocity characteristics, a theoretical relationship is developed between the peak angle of internal friction measured in plane strain, and that measured in direct shear. This relationship is shown to be born out by test results reported independently in the literature.