EFFECT OF ANISOTROPIC YIELDING ON THE FLOW LIQUEFACTION OF LOOSE SAND

Abstract

In very loose sand, the ratio M_p of shear stress to mean normal stress at the peak point of the undrained effective stress path (UESP) is very close to the stress ratio Mat the peak point of the capped yield surface. Stress ratios M_p can therefore be used in constructing yield surfaces of sands. These stress ratios have also been used in the past in evaluating flow potential of loose sand. Application of M_p for these purposes requires that factors affecting this stress ratio, and quantitative relationships for the variation of M_p with these factors be determined. In this paper, effects of the intermediate principal stress and direction of loading on M_p are investigated, and models are developed by which these effects can be quantified. It is shown that variations of M_p with these factors are similar to the variations of yielding stresses obtained from stress-strain data. Yield surfaces obtained from the variation of M_p indicated a strong dependency of yielding stresses on inherent anisotropy. Data examined in this paper also suggest that the effects of inherent anisotropy on yielding stresses are controlled primarily by the relative magnitudes of the normal stresses applied in the principal directions of material anisotropy.