Soichiro KITADA
Fundamental Study on Long-Term Land Subsidence Mechanism after Chuetsu Oki Earthquake in Kashiwazaki Plains
Satoru OHTSUKA
The people who live in Kashiwazaki city in Niigata prefecture have suffered damage of land subsidence for a long time. It`s due to decreasing ground water level. However, land subsidence wasn't dependent on groundwater after Chuetsu Oki earthquake occurred and that's a very rare phenomena. Therefore, the purpose of this study is to clarify the phenomena.
Therefore, pore water pressure was measured directly in the site which is same as preceding study and it was to determine the integrity of the previous studies. As a result, excess pore water pressure wasn't remained on the upper layer. The result is different from the past analysis result.
Analysis on this study modified to obtain each 1m parameter. However, excess pore water pressure was remained for a long time. It was same as previous result. Therefore, analysis was rerun by using the upper sand layer as the drainage boundary. As a result, there was a consistency by "excess pore water pressure at the upper layer", "ground amount of shrinkage" and "Ground surface subsidence". Land subsidence damage became bigger than a conventional analysis result. It was elucidated to continue ground shrinkage on the deep layer for a long time.
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