Pre-shear Effect on Liquefaction Resistance of Sand

Pre-shear history has been proven to be a critical factor in the liquefaction resistance of sand. In contrast to prior experimental studies in which triaxial shear tests were used to examine the effect of pre-shear on the liquefaction resistance of sand, hollow cylinder torsional shear tests were used in this study, to avoid the influence of inherent anisotropy that is inevitably produced during the sample preparation process due to gravitational deposition. A series of cyclic undrained shear tests were carried out on sand samples that had experienced different degrees of pre-shear loading. The test results showed that the liquefaction resistance of sand is greatly reduced by its pre-shear history, and a small pre-shear strain can cause sand to be much more prone to liquefaction. During the cyclic shear tests, the samples that had experienced pre-shear loading exhibited different behaviors when cyclic shear loading started in different directions, i.e. the clockwise direction and the counterclockwise direction.