Undrained cyclic triaxial tests were performed on undisturbed samples of natural soil deposits in order to investigate some of the factors affecting its liquefaction characteristics. It was shown that when the cyclic deviator stress is normalized with respect to major principal effective stress the number of cycles to liquefaction is not affected by sample size, consolidation stress, anisotropic consolidation, and grain size and density variations. However, liquefaction resistance was markedly increased by increasing over-consolidation ratio and aging. Also, sample disturbance of loose soils results in an increase, or unconservative measurement, of liquefaction resistance
