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Volume 19 (2009)
- Issue 4 Pages 235-
- Issue 3 Pages 143-
- Issue 2 Pages 67-
- Issue 1 Pages 5-
Volume 19, Issue 3
Displaying 1-3 of 3 articles from this issue
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Mitsuhiro MORI, Susumu MASUKAWA, Masaru TOKASHIKI, Hidekazu TAGASHIRA2009 Volume 19 Issue 3 Pages 143-153
Published: September 15, 2009
Released on J-STAGE: November 11, 2009
JOURNAL FREE ACCESSConventionally, the safety management of fill dams is made by means of movement observation of embedded instruments in the dam body, or water level observation in the boreholes in the surrounding hill sides. But the data obtained from these instruments are only local point data, and not necessarily sufficient to identify the anomaly point. Authors developed new technique which could grasp the anomaly place as the change of resistivity by resistivity tomography. First, numerical experiment was excused to explore the sensitivity against anomaly point. Electrodes were buried in the fill dam during construction for measurement of resistivity tomography. In the result of resistivity monitoring during test filling of the dam, a little resistivity change was observed, which would be caused by seepage of reservoir water that had higher resistivity than underground water, or by changing of temperature in the dam body.View full abstractDownload PDF (2307K) -
Katsumi OOYABU, Kentaro KIDO, Atsushi SUZUKI, Takeshi NAKAMURA2009 Volume 19 Issue 3 Pages 154-164
Published: September 15, 2009
Released on J-STAGE: November 11, 2009
JOURNAL FREE ACCESSFor speed-up of concrete placing in upper area of a concrete gravity dam, this paper discusses possibility of simplification of procedure for placing work using FEM analysis and laboratory tests, especially focusing on the following two points; (1) unification of the concrete grade which is placed to both outer and inner zone of dam body and (2) substitution of cement milk for mortar which is placed for preparation work of the horizontal construction joint surface. The results are as follows;
(1) Influence on thermal stress caused by application of rich concrete to inner zone of dam body is rather small as long as the height from the dam crest is less than 30 m, and it is thought to be adoptable to place the rich concrete to both outer and inner zone of upper part of dam body; and
(2) Shear strength of horizontal construction joint with cement milk placing is found to be less than that with mortar placing by laboratory tests. Therefore, further consideration is needed for adoption of cement milk for preparation work of horizontal joint.View full abstractDownload PDF (1536K)
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Tetsuya SUMI, Hiromi KOTSUBO, Akira KUBOTA, Isamu SANDANBATA, Toshiyuk ...2009 Volume 19 Issue 3 Pages 165-171
Published: September 15, 2009
Released on J-STAGE: November 11, 2009
JOURNAL FREE ACCESSWater turbidity is one of the biggest problems in case of reservoir sediment replenishment to the river. Moreover, the processing of the nutrients contained in the collected sediment is also another crucial problem. The purpose of our study are; how to dredge sediment from reservoirs safely, and how to produce the appropriate grain sized material from the sediment which contain very fine sediments or nutrients. We carried out field examination for spiral classifiers and replenishment tests to examine the effect of this treatment system for the reduction of water turbidity. Also we carried out laboratory flocculation and sedimentation tests against the suspended solids, and flow channel tests.View full abstractDownload PDF (1984K)
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