Abstract
This study investigates the effects of cyclic loading history on shear wave velocity and liquefaction resistance of Toyoura sand. Cylindrical specimens with relative density of 50% were subjected to isotropic consolidation up to 100 kPa, followed by 100, 1000, 2000 and 3000 drained cyclic loadings under triaxial condition with constant vertical strain amplitude of 0.1%. In order to investigate variation of shear wave velocity and liquefaction resistance of the sand specimen caused by the different number of cyclic loading histories, first, a series of dynamic measurement by trigger and accelerometer methods were conducted. It was found that the shear wave velocity of the specimen increases with increase in the number of drained cyclic loading history. Second, undrained cyclic triaxial tests were conducted on the above-mentioned specimens. The liquefaction resistance increases with a large number of cyclic loading history, and there is good correlation between shear wave velocity and liquefaction resistance. Third, in order to obtain a lower limit of shear wave velocity and liquefaction resistance, another series of experiments were performed on a specimen which has several liquefaction histories. The result shows that the smallest values of the shear wave velocity and liquefaction resistance of the specimen were measured at the second stage of liquefaction test.
