Abstract
Soils from sand boils formed during earthquakes were collected and examined to investigate the grain size distribution of the liquefied layers in the ground. However, such effectiveness of sand boils as an index has been questioned, since several observation results of sand dikes excavated in ruins revealed that the grain size distribution of soil in sand dikes differs from that in liquefied layers. In this study, the authors investigated the physical properties of soil in sand dikes, the mechanism of sand dike formation, and the relationship between sand dikes, sand boils and liquefied layers at three sites having liquefied during two earthquakes. As a result, soil particles in sand dikes were found sorted, being coarser in the lower part, and did not coincide with the grain size distribution of the soil particles in the liquefied layers or in sand boils. However, the grain size distribution of soil in sand boils was similar to that in the liquefied layers.
