2017 Volume 27 Issue 1 Pages 26-35
Few records are available internationally concerning arch dams hit by large-scale earthquakes. Many of the behavioral and damping characteristics of arch dams under strong seismic motion are not clearly known. To clarify the three-dimensional behavioral characteristics of an arch dam under seismic motion, this study analyzed the records of the A Dam, which is controlled by the Japan Water Agency. The records include micro-tremor records obtained by simultaneous multipoint measurement (at 14 locations), small-earthquake measurements obtained by seismographs placed three-dimensionally (at 6 locations), and seismic records obtained at the time of the greatest aftershock of Niigata Prefecture Chuetsu Earthquake. Based on this analysis, we determined the character frequency of the arch dam (A Dam) under seismic motion. We also accurately reconstructed the behavioral characteristics of A Dam at the time of the greatest aftershock (a magnitude of 6.5) of Chuetsu Earthquake, by means of the three-dimensional finite element method (FEM) analysis that used an improved method of coupling between the bedrock, the dam body, and reservoir. Further, based on the reconstruction analysis results, we determined the damping coefficient for the body of A Dam, and using the coefficient we conduct dynamic analysis for level 2 seismic motion.
