Factors Affecting Liquefaction Resistance and Assessment by Pore Pressure Model

Assessment of the liquefaction resistance of clean sand still involves considerable uncertainties, which are a current research topic in the field of soil liquefaction. Factors to be considered include shaking history, overconsolidation, degree of saturation and partial drainage. The effects of these factors on liquefaction resistance have been studied in the laboratory and empirical relationships are derived. This paper describes the development of pore pressure generation model similar to that of Martin et al. [18] but based on stress-controlled triaxial tests. The effects of various factors on the pore pressure generation and liquefaction resistance of clean sand are explained using the unique index of volumetric strain. The model is verified through comparisons with the results of laboratory tests. It is confirmed that the plastic volumetric strain accumulated in sand either by drained or undrained loading dominates the increase in liquefaction resistance of pre-sheared, overconsolidated and unsaturated sand. The model provides a better understanding of the physical processes leading to liquefaction of saturated and unsaturated sand with and without stress histories.