2023 Volume 33 Issue 1 Pages 16-25
We conducted NIOM analysis for the earthquake records observed at Yamaguchi regulating reservoir operated by the Japan Water Agency, and examined seismic wave velocity in the dam body. Based on the results, seismic wave velocities in the upper and lower core zones, and the upstream and downstream sides of rock zones were investigated. Then the nonlinear behavior during the relatively strong earthquake motions due to the 2005 Fukuoka-ken seiho-oki earthquake and the 2016 Kumamoto earthquake was discussed. The results revealed that the reduction of the shear rigidity during the Fukuoka-ken seiho-oki earthquake in the upper part of core zone was 35% at a shear strain of 1×10-4, and those in the rock zones were 25% at a strain of 3 to 5×10-5.
