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Volume 25 (2015)
- Issue 4 Pages 206-
- Issue 3 Pages 139-
- Issue 2 Pages 79-
- Issue 1 Pages 6-
Volume 25, Issue 3
Displaying 1-3 of 3 articles from this issue
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Hidenori MOGI, Hideki SODA, Hideji KAWAKAMI, Tatsuo OHMACHI2015 Volume 25 Issue 3 Pages 139-149
Published: September 16, 2015
Released on J-STAGE: September 30, 2015
JOURNAL FREE ACCESSWe conducted Normalized Input-Output Minimization (NIOM) method for the long-term earthquake observation records at Nagara Dam operated by the Japan Water Agency, and estimated the propagation time of the seismic waves and dynamic soil properties of the dam body. We compared our results with those in the detailed report by Sasaki et al. on the records of the 1987 Chiba-ken Toho-oki earthquake. These examinations revealed that (1) the P- and S-wave propagation times observed during the Chiba-ken Toho-oki earthquake and its aftershocks showed larger values than those observed after these earthquakes; (2) the temporal variation of the propagation times is quite small after the mainshock and aftershocks of the Chiba-ken Toho-oki earthquake; (3) the effects due to the 2011 Off the Pacific Coast of Tohoku Earthquake could not be seen in the dynamic soil properties of the dam body obtained in this study.View full abstractDownload PDF (5658K) -
Toshiyuki TEMMYO, Yuji NAKAMURA, Yuya YAMAGAMI, Tetsuya SUMI2015 Volume 25 Issue 3 Pages 150-161
Published: September 16, 2015
Released on J-STAGE: September 30, 2015
JOURNAL FREE ACCESSSince the ejector can pump up the solid mixtures with water by the negative pressure produced by the jet water injected from a nozzle, and then simultaneously transport them, practical use is expectable as a sediment removal method of the dam reservoir which contains gravels etc. However, since there are few experiences, there is little knowledge about the effect of the concentration of sediment, the length of suction and transportation pipe, and the air content in a pipeline. In this laboratory examination, the hydraulic model test of the sediment transportation system by using the ejector pump was carried out, and clarified the influences for the sediment transportation rate in the case of above mentioned conditions.View full abstractDownload PDF (2406K)
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Jyunichi ASAYAMA, Hiroyuki OHNUKI, Ryouichi YOSHIOKA, Toshihisa KASE2015 Volume 25 Issue 3 Pages 162-167
Published: September 16, 2015
Released on J-STAGE: September 30, 2015
JOURNAL FREE ACCESSInstalling horizontal joints and brace members for connecting supporting piles is essential for assembling working platforms. In case of assembling the platforms on water, most working processes are dominated by underwater works by divers. As the visibility is often low in water of dam lakes, reducing such divers' operations as much as possible has been a challenge to enhance the safety and efficiency of the assembling works. We developed a rationalizing technology to install horizontal joints and brace members above the water by improving LIBRA method which is a conventional method for assembling working platforms. This technology was applied to the construction of upgrading Kanogawa Dam.View full abstractDownload PDF (1354K)
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