ABSTRACT
The confining stress factor Kσ is used in liquefaction evaluations to extend empirical charts for liquefaction resistance to confining stresses higher than the empirical field-performance database, approximately 1 atm. Estimates of Kσ from Harder (1988) and Hynes (1988) indicated relatively large reductions in liquefaction resistance ratios with increasing confining stress. Laboratory work by Vaid and colleagues (1985, 1995) indicated higher values of Kσ. In this study, a database was developed to investigate the reasons for the broad scatter in Kσ From our study we conclude that: 1) Kσ is strongly influenced by method of deposition, stress history, aging effects, and density; 2) reconstructed, pluviated specimens in the laboratory may represent recently deposited dredged materials or recently liquefied materials; however, 3) high quality undisturbed samples are needed to determine field-relevant values of Kσ. The MCEER International Liquefaction Committee (Youd & Idriss 1997) adopted the Kσ recommendations from this study.
