Journal of Japan Society of Dam Engineers
Online ISSN : 1880-8220
Print ISSN : 0917-3145
ISSN-L : 0917-3145
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Volume 18, Issue 1
Displaying 1-5 of 5 articles from this issue
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  • Damage to Dams caused by the 2008 Iwate/Miyagi Inland Earthquake (Quick Report)
    Kazuhito SHIMAMOTO, Tatsuo OHMACHI, Hideaki KAWASAKI, Shinji IWAI
    2008 Volume 18 Issue 1 Pages 4-9
    Published: March 15, 2008
    Released on J-STAGE: October 03, 2008
    DOIhttps://doi.org/10.11315/jsde.18.4
    JOURNAL FREE ACCESS
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    The 2008 Iwate/Miyagi inland earthquake of magnitude 7.2 occurred at 8:43 a.m. on June 14, 2008. It caused earthquake damage to some dams located in the near-fault area. The dams were, for example, Ishibuchi dam, Isawa dam (under-construction), Aratozawa dam, Kurikoma dam and Koromogawa No. 1 dam. Japan Society of Dam Engineers dispatched an investigation team to those dams during June 30 and July 1, 2008. This paper describes a quick report on the damage to those dams such as large settlement and cracks caused by this earthquake.
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  • Seepage Behavior and Safety Evaluation in Embankment Dam
    Kunitomo NARITA, Katsuyuki KIMURA, Tetsuo OKUMURA
    2008 Volume 18 Issue 1 Pages 10-20
    Published: March 15, 2008
    Released on J-STAGE: October 03, 2008
    DOIhttps://doi.org/10.11315/jsde.18.10
    JOURNAL FREE ACCESS
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    Finite element saturated and unsaturated seepage flow analysis was done in this paper to study distribution of the residual pore water pressure generated in an embankment dam during a rapid drawdown and its influence on safety evaluation in the up-stream slope. The accuracy of FEM solutions was first examined by comparing them with the observed results from centrifuge model tests. Parametric studies were then conducted on several model fills with different inclinations of slope by varying the decreasing rate of the reservoir level, to understand the mechanism of seepage flow during drawdown and variation with time of the residual pore water pressure accumulated in the embankment. Instability of embankment slopes was studied for two different patterns of failure, sliding failure along circular slip surfaces due to a large residual pore water pressure and seepage erosive failure due to a large difference of pore water pressure in space, i.e. hydraulic gradient.
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  • Study on Grout Mix Proportion Control Considering Clogging Process in Dam Foundation Grouting
    Yoshikazu YAMAGUCHI, Hiroyuki SATOH, Masahiro NISHIOKA
    2008 Volume 18 Issue 1 Pages 21-35
    Published: March 15, 2008
    Released on J-STAGE: October 03, 2008
    DOIhttps://doi.org/10.11315/jsde.18.21
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    In dam foundation grouting, grout mix proportion is designed based on Lugeon value, which is an index of permeability of foundation. The "Thick or thin?" in the grout mix proportion is still important and difficult problem. Recently, researches on the optimum mix proportion of the grout are positively advanced, and a system which can automatically change the grout mix proportion, a "Variable Mix Injection System", has been developed. The system could improve the efficiency of the dam foundation grouting. In this study, the process of the injection was analyzed based on actual grouting data obtained at a dam site. In addition the method of predicting an amount of cement based grout take and the method of controlling the optimum grout mix proportion was investigated.
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  • Controlling of the Water Content of Core Material by Means of Compulsory Aeration
    Takashi ITO, Masato NUMAKUNAI, Kazuhiko ITO, Hideto HOURAI
    2008 Volume 18 Issue 1 Pages 36-47
    Published: March 15, 2008
    Released on J-STAGE: October 03, 2008
    DOIhttps://doi.org/10.11315/jsde.18.36
    JOURNAL FREE ACCESS
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    On the execution management of central impervious core of rock fill dam, it is very important to guarantee the high impervious function that is directly connected with safety of dam. The quality control of core materials is carried out by compaction as the water content is restricted the neighborhood of optimum moisture content (Wopt). The water content in this project was restricted to the range of (Wopt +1.0%)-(Wopt +4.0%) (Wwet). As the core materials collected from the field have much water content, it is necessary to reduce water content by 5.0-10.0%. In order to adjust instantaneously the water content, the compulsory aeration equipment was developed. The equipment worked satisfactory and ensured the execution progression of core.
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