Hirokazu NUNOKAWA
Research on dissimilarity subsidence mechanism of building base on the liquidizing ground repeated due to Chuetsu and Chuetsu-oki earthquake
Satoru Ohtsuka
The site investigation was executed from the damage of the Niigataken Chuetsu-oki Earthquake that had been generated in 2007 in the Kashiwazaki matsunami 2-chome in the present study. It considered it by using the vibration table model experiment of the correlativity and the dissimilarity subsidence mechanism that the ground gave to the building damage based on these investigations. Moreover, it examined compression by three axes various, it experimented on the vibration table model to understand the mechanical attribute while using the finding of liquidizing the past of liquidizing the repetition seen in Kashiwazaki City and the Kariwa village, and the mechanism was considered. The following have been understood from two experiments.
From site investigation executed in Kashiwazaki matsunami 2-chome to struck rate high, and key factor according to liquidizing almost of the building generation in stratum boundary in dune and triangular state unequal settling. The decrement effect of the acceleration according to liquidizing is not demonstrated though the dissimilarity subsidence mechanism is short in the point where the liquidizing layer thickness is small the generation time of liquidizing from the vibration table model experiment, and the amount of the subsidence is small and the acceleration is amplified. The generation time of liquidizing was long, the amount of the subsidence was large on the other hand when the liquidizing layer thickness was large, and the acceleration showed the attenuation tendency. In the stratum boundary where these two differences were large, it was able to be confirmed that the amount of the dissimilarity subsidence grew from the outcome of an experiment. This agrees to the result of the survey of the building damage, and is thought to be an occurrence of damage by a similar mechanism also in the locale.
N value of the standard penetration test and the cone penetration test did not have a big difference from a Kariwa- village local survey after the earthquake of Chuetsu, and the rise of foundation strength caused by the density increment by liquidizing was not seen. Liquefaction strength has not been repeatedly growing from the shearing examination very much though the Kariwa- village local sampling sample is similarly thought to be a rise of the relative density of the ground by liquidizing due to Chuetsu and the Chuetsu-oki earthquake from the dynamic shearing result. It agrees from the local investigation result and the dynamic shearing result in the point where the liquidizing resistance is still small there is a possibility of still liquidizing the danger of a potential liquidizing the local ground again high though Kariwa- village rice plant place district was repeatedly liquidized due to Chuetsu and the Chuetsu-oki earthquake.
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