Keywords: Tri-axial tests

In the 2007 Niigata-ken Chuetsu-oki Earthquake, ground liquefaction was severe in sandy areas, but long-term settlement occurred in soft clay in Kashiwazaki’s Shinbashi district. Even without visible damage, the ground sank 71 mm over 14 years. We studied this by boring and testing soil samples, finding the clay to be soft and highly compressible. Using a specialized computer model (TS-CM), we successfully simulated the ground’s behavior, showing that this type of clay is prone to long-term sinking after earthquakes due to water pressure buildup and delayed consolidation. These findings help predict future ground behavior in similar soils.