Abstract
A series of undrained cyclic shear tests was performed on compacted samples of Shirasu to assess the influence of grain size distribution and confining pressure on the liquefaction susceptibility. For loose samples of Shirasu, different kinds of cyclic strength characteristics were defined in this study. For the cyclic shear strength of sandy soil with gravel is independent of initial confining pressure. On the other hand, for gravely Shirasu the cyclic shear strength decreases significantly with increasing confining pressure. For all dense and compacted samples, the cyclic shear strength decreases remarkably with increasing confining pressure. However, it was recognized that decrease tendency of cyclic shear strength for Shirasu due to compaction depended on grain size distributions.
