Seismic behavior of large dams for irrigation by seismic observation records at off Miyagi [Japan] earthquake (2003.5.26)
2005
Masukawa, S.(National Inst. for Rural Engineering, Tsukuba, Ibaraki (Japan)) | Nakanishi, N.
This paper describes the seismic behavior of 25 large dams for irrigation based on records of seismic observation at off Miyagi earthquake (2003.5.26). The seismic behavior of these dams are investigated by the loci of seismic acceleration waves on up-downstream and longitudinal directions, the relationships between maximum accelerations to upstream-downstream direction and to longitudinal direction, the relationships between input accelerations and amplification ratios of acceleration, and power spectrum of seismic acceleration waves. The main results are as follows. The upstream-downstream accelerations at crests are not always greater than those on other two directions (longitudinal and vertical direction). Seismic acceleration waves are amplified by their propagation throughout the dam body. The frequency component that corresponds to the eigen frequency of the dam body is amplified by propagation of seismic acceleration waves throughout the dam body. In the fill dam, the eigen frequency of a low frequency for power spectrum appears at the crest of dam. The eigen frequency of a higher frequency for power spectrum appears at the crest of gravity dam than these of the power spectrum at the fill dams. The dam site configuration and the rigidity of dam body and foundation influence the seismic behavior of the dam.
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