A comprehensive program of field, laboratory and analytical investigations was carried out to assess the potential for liquefaction of the foundation soils and seismic stability of Duncan Dam. Duncan Oam is located on Duncan River in southeastern British Columbia, Canada. The 39 m high zoned earthfill dam is founded on a thick sequence of sands, silts and gravels. The liquefaction studies were carried out in two phases between 1988 and 1992 to characterize in detail the engineering properties of the foundation soils; and to assess its potential for triggering liquefaction, and the post liquefaction stability and deformation of the dam using parameters based on two approaches; one a site specific laboratory based direct method (Lab.method) and the other an indirect method (Seed\u27s method) which is based on field penetration data and field experience during past earthquakes. This paper describes some advanced aspects of the field and laboratory investigations including laboratory testing of undisturbed soil samples obtained after freezing the ground insitu. The influence of confining stress (K0) and initial static shear stress (K0) on liquefaction were investigated and site specific correlations for K0 and K. are presented. The laboratory investigations indicate that the residual strengths of the liquefied sand is a function of initial consolidation stress
