Transactions of The Japanese Society of Irrigation, Drainage and Rural Engineering
Online ISSN : 1884-7242
Print ISSN : 1882-2789
ISSN-L : 1882-2789
Volume 78 , Issue 6
Showing 1-11 articles out of 11 articles from the selected issue
Research Papers
  • Yuqing ZHAO, Tatsuya KOUMOTO, Fumiyoshi KONDO
    2010 Volume 78 Issue 6 Pages 437-443
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    Recently, geopolymer has been a noteworthy material which can be used as a replacement for portland cement. The mechanical characteristics and consistency of the geopolymer are strongly affected by its chemical components of fly ash. The variations in compressive strength of geopolymer due to the CaO added fly ash were investigated in this paper. The compressive strengths of geopolymer were increased with an increase in the curing period, and the characteristics changed from the one of plastic soil material to brittle material such as concrete, regardless of CaO content. Also, the results of compressive strength and modulus of deformation showed their maximum value in the case of 8-10% CaO content. From this result, the maximum characteristics of the strengths were assumed to be exerted in case which the water draining process of geopolymer was balanced with the water absorbing process of additional CaO.
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  • Sho KIMURA, Seiichi GIBO, Shinya NAKAMURA
    2010 Volume 78 Issue 6 Pages 445-453
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    The average shear strength parameters along the slip surface (c´, φ´) of the four Shimajiri-mudstone landslides having different slide patterns have been obtained by two methods involving an estimation method using the shear strength diagram of landslide soils and an ordinary method using the results of laboratory shear tests of soil samples. The deference of the two average shear strengths was small in the case of the landslides where the residual and fractured-mudstone peak strengths had been mobilized, while the two methods produced close agreement in case of the landslides where the residual and fully softened strengths had been mobilized. Although, the determination of appropriate c´, φ´ is done using the measured shear strength of slip surface soil as a fundamental rule, when it is difficult to do it due to certain restrictions, c´, φ´ can be effectively estimated using the shear strength diagram.
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  • Kenji OKAJIMA, Junichi IMAI, Tadatsugu TANAKA, Toshiaki IIDA
    2010 Volume 78 Issue 6 Pages 455-464
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    Damage to piles in the liquefied ground is frequently reported. Buckling by the excess vertical load could be one of the causes of the pile damage, as well as the lateral flow of the ground and the lateral load at the pile head. The buckling mechanism is described as a complicated interaction between the pile deformation by the vertical load and the earth pressure change cased by the pile deformation. In this study, series of static buckling model tests of a pile were carried out in dried sand ground with various thickness of the layer. Finite element analysis was applied to the test results to verify the effectiveness of the elasto-plastic finite element analysis combining the implicit-explicit mixed type dynamic relaxation method with the return mapping method to the pile buckling problems. The test results and the analysis indicated the possibility that the buckling load of a pile decreases greatly where the thickness of the layer increases.
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  • Masahiro NAKAJIMA, Masato NAKAMURA, Yutaka HIROSHIGE
    2010 Volume 78 Issue 6 Pages 465-477
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    This paper aims to analyze the formative processes and the current state of a collaboration between ‘outsiders’ and local residents in a System of Rural Regional Environmental management from the view point of human networks. The system seeks to solve the problem of abandoned farmlands led by a group of university students (outsiders). We chronologically classified a total of eighty-nine activities addressing the issue of abandoned farmlands by utilizing three concepts: ‘calculated devices’ (e.g. the making of relations between a group of university students and local residents and strengthening these relations), ‘assistance/participation’, and ‘voluntary interaction/desire’. Based on this analysis, we: 1) developed an understanding of the formative processes as well as the current state of the collaboration between a group of university students and twenty seven local residents from an individual perspective; 2) identified ten key individuals who played a significant role in the activities examined and revealed their characteristics and motivations; 3) suggest that an existing NPO and informal relations between the local residents played a major role in the formation of collaborative networks; 4) argue that the perceived characteristics of the students (e.g. ‘youthful’, ‘inexperienced’) and the Mori-Mori club (e.g. unstable) contributed to the maintenance and expansion of the collaboration between ‘outsiders’ and local residents.
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  • Takashi OHKUBO, Yoshiaki HIDESHIMA, Yukoh SHUDO, Kazuhiko OHMIYA
    2010 Volume 78 Issue 6 Pages 479-491
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    A study was conducted on a system to refine biogas generated from a biogas plant, which uses cow slurry as its main ingredient, and use the bio-methane as a regional energy supply source. Based on the data obtained by the demonstrative operation of the biogas plant and bio-methane production experiments, a bio-methane production plant that can process waste from 1,000 dairy cows was assumed, and optimization of plant operation was attempted using the linear programming method with maximum environmental friendliness (reduction of greenhouse gas emissions) and economic efficiency (management balance of the plant) as the target functions. The results revealed that plant operation methods varied according to the target of optimization. Environmental friendliness and economic efficiency were in a trade-off relationship with each other, but in the case where the greatest importance was placed on economic efficiency, greenhouse gas emissions were equivalent to that in the case where the greatest importance was placed on environmental friendliness itself. However, the values of economic efficiency were negative in both cases, indicating that it is difficult to make the plant management economically feasible under the current circumstances. To make the plant management balance positive, it is necessary to take measures, such as reduction of plant construction costs and exemption from interest costs. In addition, as a future direction for such regional bio-methane use, a micro grid system with a dispersed power source using bio-methane as raw fuel was presented.
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  • Toshikazu HORI, Yoshiyuki MOHRI, Kenichi MATSUSHIMA, Mitsuru ARIYOSHI
    2010 Volume 78 Issue 6 Pages 493-503
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    In recent years the increase in the number of heavy rainfall occurrences such as through unpredictable cloudbursts have resulted in the safety of the embankments of small earth dams needing to be improved. However, the severe financial condition of the government and local autonomous bodies necessitate the cost of improving them to be reduced. This study concerns the development of a method of evaluating the life cycle cost of small earth dams considered to pose a risk and in order to improve the safety of the downstream areas of small earth dams at minimal cost. Use of a safety evaluation method that is based on a combination of runoff analysis, saturated and unsaturated seepage analysis, and slope stability analysis enables the probability of a dam breach and its life cycle cost with the risk of heavy rainfall taken into account to be calculated. Moreover, use of the life cycle cost evaluation method will lead to the development of a technique for selecting the method of the optimal improvement or countermeasures against heavy rainfall.
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Technical Papers
  • Ken HIRAMATSU, Shinichi NISHIMURA, Hideyoshi SHIMIZU, Yoshinobu NAKANE ...
    2010 Volume 78 Issue 6 Pages 505-514
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    Impact of concrete lining of channel bed with eco-friendly works, i.e. fish pools and fish habitat blocks on fish biota in Ooe drainage channel is discussed based on the ecological, hydraulic and water quality investigations from 2003 through 2007. The effectiveness of these eco-friendly technologies is also evaluated. As a result, the followings become apparent; 1) Several species which are suitable for improved channels, especially in their spawning, e.g. Pseudorasbora parva, Gambusia affinis affinis, Squalidus chankaensis sp. and Rhinogobius sp. tend to increase relatively and the species e.g. Oryzias latipes and Channa argus decrease oppositely. 2) Fish biota settles down to a certain level after 3 or 4 years after improvement of channel. 3) Fish show their preference to eco-friendly technologies like fish habitat block and fish pool and also utilize them as their habitat during non irrigation period, and 4) the total number of fish tends to somewhat decrease at large, but the number of species tends to increase contrarily in the channel through improvement with eco-friendly works.
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  • Hideto FUJII, Busia DAWUNI, Fulera TAHIRU, Macarius YANGYUORU
    2010 Volume 78 Issue 6 Pages 515-522
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    The experiments are carried out in a rainy season in 2008 to compare the differences of crop water productivity by three rice cultivation methods, which are rainfed upland, rainfed lowland and irrigated rice. Three study sites, Ashaiman, Nyankpala and Kpong are selected from three different agricultural climate zones in Ghana. The following findings are obtained from the experiments. 1) The water productivity of rice was shown as 0.02-0.40kg/m3 in rainfed upland, 0.28-0.53 kg/m3 in rainfed lowland and 0.24-0.66 kg/m3 in irrigated rice. There was a significant difference on water productivity due to differences of rainfall in upland rice. On the other hand water productivity of rainfed lowland indicated that it does not compare favorably even irrigated rice. 2) Although water productivity was higher with increasing water input, it has shown the peak in 650mm of water input and it tended to be lower with increasing of water input in this experiment.
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  • Takehisa MORI, Tetsuo NAKAYA, Akio ISHIGAMI, Tomotake KATO
    2010 Volume 78 Issue 6 Pages 523-530
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    The study of small-scale concrete canals which had been repaired using simple methods under direct management by farmers or facility managers revealed that the main cause of deterioration of these canals was water leakage caused by failures of joints between sections of the concrete. And the study also revealed that the usual repair methods were insufficiently durable and simple. To solve these problems, a simple repair method was developed in which the canal joints are covered with structural bonding tape and sealant to prevent water leakage. This method satisfied the performance requirements (leak prevention, adhesion, and allowing expansion and contraction of the joint). Moreover, the developed method made farmers possible to repair canal joints in a short time, and no defects in the repaired joints appeared for at least 2 years.
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  • Hiroyuki MATSUI
    2010 Volume 78 Issue 6 Pages 531-536
    Published: December 25, 2010
    Released: December 25, 2011
    JOURNALS FREE ACCESS
    I examined the accuracy of the common net long-wave radiation equations adopted in Penman-type evapotranspiration equations. Net longwave radiation was calculated from upward and downward longwave radiation fluxes observed in Tateno, Japan. The following became apparent. 1) The equation proposed by Penman shows the minimum RMSE of all the equations used, although its estimates are more likely to vary widely; 2) the two equations recommended by the FAO tend to underestimate net longwave radiation flux throughout a year; 3) annual potential evapotranspiration, calculated using Penman's net longwave radiation equation, appears to show less error than other equations, whereas the FAO's net longwave radiation equations might overestimate annual potential evapotranspiration by approximately 100 mm per year; 4) parameters of net longwave radiation equation should be calibrated based on high-accuracy observations in Japan.
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