| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Outline of Final Research Achievements |
We applied the NIOM method (Normalized Input--Output Minimization) to long-term earthquake observation records from such as Shitoki Dam and Aratozawa Dam to determine the propagation velocities of seismic waves in the embankment, and investigated changes in soil properties. As a result, we showed that (1) the velocities of S- and P-waves decreased significantly during strong ground motions due to the 2008 Iwate-Miyagi Nairiku earthquake and the the Great East Japan earthquake of 2011; (2) in subsequent minor earthquakes the propagation velocity increased more or less in proportion with the logarithm of the number of elapsed days; (3) the damping ratio in the dam body also increased due to the principal motions of the mainshocks and decreased after them in the similar manner as seen in the results of the propagation time; and, (4) an FE/BE analysis using the estimated propagation velocities was conducted and wave-propagation characteristics in the embankment was discussed.
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