新潟地震・中越地震·中越沖地震時の液状化による信濃川堤防被災について

抄録

This report describes the embankment damage in the Shinano River caused by the Chuetsu-oki Earthquake, and explains how the embankment was damaged in the liquefaction of ground. In particular it clarifies that, among six dyke sections damaged in the liquefaction caused by the past two big Earthquakes of Niigata and Chuetsu, the only one suffered damage from the Chuetsu-oki Earthquake, and why the only one damaged while another five did not damage. It is concluded that the possibility of the embankment damage from the liquefaction is affected by 1) magnitude of earthquake; 2) geological structure subjacent to the embankment; 3) groundwater level; 4) the saturation fraction of the dyke soil influenced by antecedent precipitation, groundwater level and water level of river; and 5) effect of restraining the lateral fluxion of ground. It also includes some suggestions to identify the weak section of embankment against the earthquake and to improve the resistance to the earthquake.