Abstract
The surface layers of alluvial plains in Kagoshima are almost covered with the alluvial secondary Shirasu which is eroded by the rainfall, transported from the Shirasu pleatues and deposited on the alluvial plain. In this paper the dynamic properties of alluvial secondary Shirasu ground are referred and discussed by the results of previous research work from a new view point, and a method is proposed to estimate the liquefaction potential of alluvial secondary Shirasu ground. The main results are summarized that (1) the decrease of dynamic shear stress ratio with depth is different from usual sandy soil, (2) by using the inherent decreasing coefficient of shear strength for the alluvial secondary Shirasu and twice N-value obtained by SPT, the liquefaction potential can be reasonably estimated, and (3) the liquefaction potential in the southern part, near coastal line and along rivers, Kagoshima City is relatively higher than one in the northern part.
