Constitutive modeling of principal stress rotation associated with sand under simple shear loading

Abstract

AbstractAn elasto‐plastic constitutive model is proposed to account for the effect of principal stress rotation that commonly occurs and significantly influences soil behavior. The model is based on a concept of adding plastic strain increments obtained from two mobilized planes: a plane of maximum shear stress which swings as the principal stress rotates, and a horizontal plane which is spatially fixed. Models based on the plane of maximum shear stress alone are particularly sensitive to horizontal effective stress ratioK0(=σ′x/σ′y), whereas the proposed model gives a similar skeleton behavior for soils at the same density and mean effective stress, regardless of the value ofK0, as observed in laboratory tests. The model is firstly calibrated by data from drained and undrained monotonic and cyclic Direct Simple Shear (DSS) tests onK0‐consolidated specimens of Nakdong River sand in loose and dense states. The capability of the proposed model in modeling of the conventional liquefaction effects: initial shear stress conditionα(=τ′xy/σ′y) withKαcorrections, and initial confining stress conditionσ´ywithKσcorrections, is also emphasized in this paper.