YIELDING AND FLOW LIQUEFACTION OF LOOSE SAND

Abstract

The relationship between the shapes of the yield surface and the undrained effective stress path (UESP) of loose sand is investigated for triaxial loading conditions. It is shown that the UESP can be used in the construction of capped yield surfaces for sands. The stress ratio M_p, measured at a point where the UESP of loose sand reaches a peak, has been incorporated as a material parameter in the analytical relationship by which the yield surface is defined. The variations of M_p with void ratio, state parameter, and consolidation stresses are examined and compared with previous studies, in cases where such studies exist. It is shown that M_p is strongly influenced by soil dilatancy and anisotropy and its variation is remarkably consistent with the variation of soil strength and yielding stresses. Quantitative relationships for the variations of M_p are then introduced; these have been used elsewhere in constructing yield surfaces and modeling the constitutive behavior of sands. In addition to their use in modeling sand behavior, the yield surfaces and quantitative variations of M_p obtained here can be used in quantitative assessments of the susceptibility of loose sandy soils to flow liquefaction.