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Volume 3 (1993)
- Issue 12 Pages 4-
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- Issue 9 Pages 9-
Volume 3, Issue 9
Displaying 1-6 of 6 articles from this issue
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Kaoru NIWA, Masayosi KIROSE, Takahiro MIYAI, Yushi AMANO1993 Volume 3 Issue 9 Pages 9-17
Published: March 15, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSGlobal warming resulting from increasing concentrations of atmospheric carbon dioxide and other trace gases may alter various hydrologic process in drainage basins. Global warming effects on water resources may depend on characteristic of each region, precipitation and vegetation, etc. So present flow regime is compared in three basins, which are dominated by different major phenomena, rainy season (baiu), typhoon and snow accumulation and melt. On some scenarios, sensitivity of water resources is evaluated at each basin by an index of dam necessary capactiy to secure necessary flow at downstream point to examine global warming effects and the differences are compared in the three basins.View full abstractDownload PDF (1651K) -
Kei ITIKAWA, Mitumasa TANNO, Kiyoshi KATAWAKI, Susumu MORIYA, Shuichi ...1993 Volume 3 Issue 9 Pages 18-28
Published: March 15, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn Japan stainless steel has been applied widely for reducing maintenance in dam outlet equipment. However the galvanic corrosion between stainless steel and carbon steel have been discussed.
We surveyed actual state of galvanic corrosion at existing dam site, and corrosion phenomena was analyzed. With these results, galvanic corrosion was predicted with mathematical simulation.View full abstractDownload PDF (3050K) -
Syoichi HONDA, Masamichi WADA, Yoichi FUKUMOTO1993 Volume 3 Issue 9 Pages 29-40
Published: March 15, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSWhen a crane is utilized for concrete transport in the dam construction, the process of concrete conveying and placing is simple repeated but long time. So human errors and accidents may be possible. In addition workers are in danger of hit against transfer-car and bucket.
In order to improve safety and efficiency, automatic operation systems of transfer-car and bucket carrier and remote control buckets have been developed. These new systems are not only advantageous in performance but also in cost-saving and safety, and can be applied to most of dam construction sites.View full abstractDownload PDF (3452K) -
Hikaru TAKEUCHI, Minenori TAKEYAMA, Masahiko KOSHIKAWA1993 Volume 3 Issue 9 Pages 41-50
Published: March 15, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSRecently, thermal cracks due to the heat of hydration for massive concrete structures have become controversial problems in response to the requirements of high durability. Several measures have been raised in order to control such thermal cracks such as precooling method, postcooling method, modification of concrete proportions, etc. Especially, precooling method is thought to be the most effective way to decrease thermal stresses in the concrete structures. The authors have initiated the fundamental research on precooling method with Dry Ice. And a prototype test was conducted in order to verify the cooling efficiency, manufacturing efficiency of cooled concrete, concrete strengths and concrete neutralization degrees when using an actual batching plant. This paper discribes the results of the prototype test of this precooling method, which show that this method is feasible and reliable.View full abstractDownload PDF (2297K) -
Toshio JOTATU, Hitoshi YOSHIDA, Takashi OIKAWA1993 Volume 3 Issue 9 Pages 51-65
Published: March 15, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn Japan, the lift thickness of concrete placed under the RCD construction method is generally adopted at 0.5 to 0.75m and the thin layer spreading method using bulldozers is employed to eliminate segregation of concrete due to dumping from dump trucks.
Now that “the thin layer spreading method” whereby concrete is spread to a thin layer of about 27cm in depth was widespread as a means of eliminating the possibility of concrete segregation, increasing the lift thickness to about 1.0m (0.25 *4 layers) can augment the rate of concreting and reduce green cut and mortar spreading.
In the Ryumon Dam construction, the lift thickness of 0.75m, originally chosen for concrete placement (using vibratory roller BW-200), was increased to 1.0m in June 1991 after repeated concreting tests (using a new vibratory roller SD-450). When the increased lift thickness was introduced, the completed section of the dam structure had attained EL. 239.00m, or 56% of the entire construction work.
Concreting tests with the 1.0m lift thickness and actual placement to this thickness are outlined in the sections which follow.View full abstractDownload PDF (2262K) -
Norihiko NAKAMURA, Yoshihiro YAMASHITA, Masayuki KITAMAKI1993 Volume 3 Issue 9 Pages 66-76
Published: March 15, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn The Lake Biwa Comprehensive Development Project, in order to prevent the area by the lake from flood damage, we had constructed the levees with a road for management, internal drainage facilitied, and so on.
Though these facilities are indespensable to protect precious lives and property of the residents by the lake, on the other hand, construction of these facilities inevitably destroy a part of reed communities.
Therefore, besides these flood control projects, we decided to plant reed in the lake shore near the levees and seemed to be suitable for growing of reed. So, we made the preliminary experiment of planting reed from 1982 to 1986, and carried out the work of planting reed from 1987 to 1991.
As a result, the planted reed communities are not inferior to the natural reed communites in growth and the planted reedbeds fulfill the same function for the birds as the natural reedbeds do. The total area of planted reed communities is about 5ha.View full abstractDownload PDF (3952K)
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