Abstract
Six series of tests were performed to investigate the effects of preshearing on the liquefaction characteristics of saturated sand samples subjected to cyclic shear stress. Five types of shear stresses were previously applied to the samples, and thereafter a constant double amplitude cyclic shear stress which had a fixed stress ratio of σD/2·σ0=0.113 was applied until liquefaction occurred. Through these experiments, it was found that within the range of the tested stress level, the curves showing the relationship between the magnitude of preshear stress and the liquefaction resistance have a peak, and that this phenomenon can be attributed to the outcome of the combined effects of previous small preshear and large preshear. It was also found that this change in liquefaction resistance caused by preshearing can be explained by superposing the two characteristic effects of the same-direction and the opposite-direction preshearing.
