Evaluation of Settlement Behavior and Collapse of Fujinuma Earth-Fill Dam by the 2011 off the Pacific Coast of Tohoku Earthquake

Abstract

By the 2011 off the Pacific coast of Tohoku Earthquake, Fujinuma dam collapsed, and the disaster caused many deaths. This study, performs a dynamic response analysis of Fujinuma dam, and calculates residual deformation amount by residual deformation analysis applied Watanabe-Baba method assumed arc slip, and compares the measured crest settlement with the observed crest displacement leading to the dam collapse. As a result, it is possible to estimate the strength parameters of Fujinuma Dam, but if not taking into account the reduction in strength crest settlement amount is fairly small, and if strength reduction occurred the crest settlement reached to the difference between the heights of the dam crest and the high water level when collapsing. The major reason why the large crest settlement has occurred in the dam, are the density decreases and lack of strength due to no compaction. The residual deformation analysis was performed, it is possible to explain the residual settlement of Fujinuma dam, and it could prove to be high applicability of the residual variant.