Analytical definition of collapse surface in multiaxial space as a criterion for flow liquefaction occurrence

Prediction of flow liquefaction occurrence in multiaxial stress space is presented in this paper. The closed-form relation analytically attained by means of Dafalias-Manzari constitutive equations gives the flow stress ratio as a function of model parameters, state parameter, direction of undrained loading and especially initial condition of consolidation. These proposed flow condition can predict the occurrence of flow liquefaction initiated by any loadings whether the soil is consolidated isotropically or anisotropically. Suggested predictions are compared with the results of triaxial tests performed on Hostun RF sand. The results show that increasing consolidation stress ratio leads to flow stress ratio increase.