Sensitivity analysis on long-term subsidence of soft clay due to The Niigataken Chuetsu-oki Earthquake in 2007

抄録

The long-term settlement of the ground after the Niigataken Chuetsu-oki Earthquake in 2007 was observed at Shinbashi in Kashiwazaki city. To study the seismic deformation mechanism and long-term post-earthquake settlement, this study carried out ground investigations such as drilling survey on the observation site and indoor element tests for sampled soil. The results showed that the sampled soil was very soft, strongly compressible, and relatively highly-structured. Subsequently, the ground subsidence behavior was simulated through soil-water coupling elastoplastic finite element (FE) analysis using the Transformation Stress-Cyclic Mobility (TS-CM) constitutive model developed by Zhang et al. (2007). The FE simulation results were in good agreement with the on-site site subsidence observation data and the subsequent settlement was predicted forward. Based on the simulation results, sensitivity analysis was conducted on two key parameters λ and κ, and it was concluded that λ is more sensitive to the subsidence amount. In addition, the impact of parameter uncertainty on model uncertainty was also discussed and it was concluded that both λ and κ are moderately conservative and nearly low dispersion for subsidence results, but the dispersion of parameter λ was relatively lower than κ, although parameter λ was more sensitive to the subsidence.