Abstract
A series of undrained cyclic triaxial tests were performed on various types of high-quality undisturbed gravelly samples recovered by the in-situ freezing method. The undrained cyclic shear strength obtained from these tests was reviewed and related to shear wave velocity measured in the field. Similar test results determined by other investigators were also adopted for establishing a correlation. Based on the review of these test results, the following conclusions were drawn. For the case of gravels of Holocene Epoch, a fairly good correlation could be found between the undrained cyclic shear strength and shear wave velocity, in such a way that the undrained cyclic shear strength increases with an increase in the shear wave velocity. The data for Pleistocene gravel, however, indicated two separate groups. One basically coincides with the correlation of Holocene gravel. The data from the other group indicated that the liquefaction strength is much higher than that of Holocene gravels for the same value of shear wave velocity. In order to correct the effect of confining stress on this correlation, a normalized shear wave velocity, VS1, in terms of the effective vertical stress was introduced. Similar good correlations were found between VS1 and the undrained cyclic shear strength. These correlations can be well expressed with empirical equations proposed by the authors. In the case of Pleistocene gravel, however, these equations indicate the lower boundary of undrained cyclic shear strength.
