Two-surface plasticity prediction of the cyclic resistance of a medium dense sand under water inflow condition

Abstract

Liquefaction has been primarily interpreted as an undrained phenomenon and liquefaction susceptibility assessment procedures are largely based on the undrained hypothesis. However, analytical, experimental, and field evidence have revealed the importance of co-seismic water flow. If water flow causes localized volumetric expansion during an earthquake, for instance at the interface of a liquefiable layer with an overlying layer of lower permeability, it can facilitate the manifestation of liquefaction. To understand the implications of drainage on the co-seismic cyclic behaviour of sand, the element level response needs to be evaluated and quantified using appropriate constitutive models. In this paper, experimental results from cyclic triaxial tests on Hostun sand under undrained and partially drained conditions, imposed through constant ratios of volumetric strain rate, are studied. The two-surface plasticity model of Dafalias and Manzari (2004) is calibrated in triaxial space using the undrained monotonic and cyclic test results and then assessed for its ability to simulate the partially drained cyclic experiments. The results of this assessment provide insight on the performance of two-surface plasticity models that are calibrated using cyclic undrained tests when predicting soil behaviour under partially drained conditions. Implications for constitutive model calibration and the reliability of numerical simulations of earthquake-induced liquefaction are discussed.