Static Liquefaction of Sands under Isotropically and K0-Consolidated Undrained Triaxial Conditions

Abstract

By using the state-dependent strength criterion and dilatancy function, a state-dependent nonassociated elastoplasticity hardening model was proposed to unify modeling the constitutive relationships of sands with different initial void ratios. According to the second-order work theory, the criteria for predicting the potential instability and static liquefaction of sands were obtained. The proposed model and criteria were used to predict a series of isotropically consolidated and K0-consolidated undrained triaxial tests. The results showed that the potentially unstable point and the onset of static liquefaction under undrained conditions coincided with the attainment of a deviatoric stress peak in very loose sand, whereas, with the decrease of the initial void ratio, the onset of static liquefaction fell behind the potential instability. When the sand specimen was dense enough, static liquefaction did not occur, although the stress state was located inside of the potentially unstable region. The potential instability and static liquefaction occurred before the effective stress reached the failure surface, and they were the precursors though not the results of the sand failures.