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Volume 2007 (2007)
- Issue 249 Pages 231-
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Akira KOBAYASHI, Ryota NIWA, Tomoya YANAGIMOTO, Kiyohito YAMAMOTO, Shi ...2007 Volume 2007 Issue 249 Pages 231-238
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSAlthough the non-destructive testing method for concrete structure has been developed so much, the one for soil structure has not been examined well. When the leakage of water through the embankment is found, the water passageway and the flow-regime have to be understood for the countermeasure and maintenance planning. In this paper, the method to infer the water table in an embankment by the elastic wave exploration which has been used intensively for the geological survey was studied. The theory used for the impact echo method for the concrete structure was applied to infer the location of the reflection point. The result of frequency analysis was used for the inference. Moreover, since the power is dependent on difference of the acoustic impedance between layers, the ratio of power to the maximum one was plotted to emphasize the location of reflections. By comparing with the results from the high density electric exploration, it was found that the newly proposed method was very useful to infer the situation of water distribution in an embankment.View full abstractDownload PDF (2791K) -
Hiroshi MORI, Yoshimi OGAWA2007 Volume 2007 Issue 249 Pages 239-246
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSWe had developed a liquefaction analysis program by Distinct Element Method (D.E.M.), and applied that method to a river dike damaged by the 1995 Hyogoken-Numbu earthquake and an urban river dike with a revetment managed in Tokyo or Osaka. The actual damaged measured vertical permanent displacement of embankment crest could be comparable with the result of analysis. The vertical displacement of embankment crest with a revetment utilized the ground improvement method with steel pipe pile and the zone occupied liquefied areas of ground foundation for the seismic resistance at riverside land, were smaller than those values of river dike with a revetment before the seismic resistance construction. Also, the effect of ground improvement planning to construct at land side was observed by this analysis. Therefore, this analysis program proved satisfactorily enough estimation for the seismic resistant method.View full abstractDownload PDF (1910K) -
Based on a survey of Ohshima-area Jouetsu-shi Niigata, JapanHiroyuki ARITA, Toshiya OHKURO2007 Volume 2007 Issue 249 Pages 247-254
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSThe farmland policy in Japan must respond to the instability of long-term food supply and demand, though it faces a structural excess of rice products in the short-term. As a solution to this problem, the authors have proposed that abandoned paddy fields be maintained by extensive management in a state where they can be used for farming at any time. In this paper, we aim to evaluate the availability of tree-invaded abandoned paddy fields from an economic viewpoint. A lumbering experiment and case research were carried out, and the relation between the restoration cost of abandoned paddy fields and their ages was modeled based on this research. As a result, the following points were clarified.(1) The cost of restoring abandoned paddy fields exceeds the cost of restoring those invaded only by grass, and the cost of restoring dry farm lands exceeds that of restoring wet farm lands.(2) There is no glaring disparity in aggregate total cost between restoring fields decades after they have been abandoned and the cost of continuing annual maintenance and extensive management designed to maintain the fields in a condition where they can be used at any time.View full abstractDownload PDF (1433K) -
Study based on a survey of Ohshima-area Jouetsu-shi Niigata, JapanHiroyuki ARITA, Toshiya OHKURO2007 Volume 2007 Issue 249 Pages 255-260
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSIn the farmland policy of our country today, we must adjust the unstable factors of long-term food supply and demand, while the structural excess of rice crop products is held short-terminable. As a solution for such problems, the authors have proposed the extensive management as a method for the agricultural land resource maintenance. In this paper, the proposal of the method which performs extensive management was tried based on the survey of the tree invasion into abandoned paddy fields, preventing trees' enlargement. It turned out that invaded trees have the following characteristics.(1) They are pioneer type trees.(2) Species of invaded trees differ greatly between dry farm lands and wet farm lands.(3) As for the number of trees and the tree volume, an dry farm land trend to exceed a wet farm land. And as a result of examining based on these, in order to manage abandoned paddy fields simply, eliminating tree vegetation, continuation of the disturbance by annual fallow cultivation etc. was considered to be an effective method.View full abstractDownload PDF (3506K) -
Isamu NATSUKA, Masaru TOKASHIKI, Mitsuhiro MORI, Akio ISHIGAMI2007 Volume 2007 Issue 249 Pages 261-267
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSFor repair and longer use of existing concrete canals, an effective method to prevent water leak through joints of canal is needed. Authors have developed a repair method which enhances stability, durability and watertightness of joints with a newly invented section shape of the filling material made of synthetic rubber with high elasticity. Stress distributions in the joint material of various section shapes are examined by FEM analyses for the cases with and without compression from the canal. It is proved that the tensile stress on the surface of the joint material can be prevented for all the cases with a hollow rim structure and appropriate shape and size of apertures. Since the compression state is always maintained on the joint surface exposed to the atmosphere, ozone will not deteriorate the synthetic rubber and high durability of the joint material is expected.View full abstractDownload PDF (3024K) -
Kouhei ABE, Masahiro HYODO, Toshio SATO, Tsuguhiro NONAKA2007 Volume 2007 Issue 249 Pages 269-275
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSPhosphorous adsorption concrete is a water purification material that is developed to remove the phosphorus in polluted water. It is main purpose of this research to establish the recycling use method of the phosphorous adsorption concrete, especially after finished using for water purification. Ordinary concrete, phosphorous adsorption concrete and phosphorous adsorption concrete mixed with natural zeolite were soaked in the river for certain periods. After brought out them from the river, the recycle uses as a seedbed and as a fertilizing material were examined into the experiments. Firstly, it was confirmed that the amount of bio-films attached to the phosphorous adsorption concrete clearly increased when soaked each specimen in actual river. Secondly, each specimen brought out from the river was verified as the seedbed and as the fertilizing material. As results, it was confirmed that phosphorous adsorption concrete had growth promotion effect for the vegetation. Furthermore, the phosphorous adsorption concrete mixed with natural zeolite showed increasing of the growth promotion effect by the cation exchange ability.View full abstractDownload PDF (1987K) -
Tamotsu NAKANDAKARI, Anshun YOSHINAGA, Kazuhito SAKAI, Yasuhiro AKIYOS ...2007 Volume 2007 Issue 249 Pages 277-283
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSSuspended soil runoff from agricultural basins has caused sea water pollution in coral and island ecosystems in Okinawa, so suspended soil runoff management is required for the conservation of the sea environment The purpose of this study was to research suspended soil runoff in a sedimentation tank. For the purpose of this study, field observation was conducted using a real sedimentation tank for many rainfall events. Discharge and water sampling during a rainfall event were observed, and suspended soil concentration and suspended soil grading were analyzed. From the observed results, soil balance in the sedimentation tank, trap efficiency, and the inflow-capacity ratio were calculated. In conclusion, the results indicate that a part of input fine soil (<75μm) passes the sedimentation tank. The inflow-capacity ratio is also found to be an essential parameter useful to estimate trap efficiency of suspended soil in a sedimentation tank.View full abstractDownload PDF (1529K) -
Qin ZHANG, Shigeya MAEDA, Toshihiko KAWACHI2007 Volume 2007 Issue 249 Pages 285-292
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSAn optimization model is presented in order to allocate irrigation water, which is withdrawn from a river, to paddy field blocks in an irrigation system. A fuzzy linear programming is employed in the model formulation for dealing with uncertainties due to randomness of hydrologic and hydraulic parameters and fuzziness in management goals. In addition to the two objectives on minimization of irrigation water withdrawal from the river and maximization of total rice yield, considered in our last study, minimization of risk of water shortage in each block of paddy fields is taken into account to derive local benefit. Fuzzy sets with appropriate membership functions are defined to mathematically describe vagueness in achievement level of those competing management goals. The minimum-operator is adopted as a fuzzy decision, so that a solution which is adequately balanced among the three goals can be obtained. The model is applied to a hypothetical irrigation district, resulting in clarifying the effectiveness of consideration of water shortage risk in the irrigation water allocation.View full abstractDownload PDF (1243K) -
Nobuo FUJITA, Yoshiyuki MOHRI, Hisato SUZUKI2007 Volume 2007 Issue 249 Pages 293-303
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSPipeline that formed with flexible joints has a high safety to a differential settlement or a seismic displacement on soft ground by the effect of each joint reaction. However, buried pipe joints subjected to seismic motion on site have scarcely ever been investigated because of internal water or underground condition, so the behavior has not been clarified enough. This paper discusses the allowable range of joint for expansion and bending. In situ survey of earthquake-damaged pipelines and model shaking test were carried out. Results are summarized as follows:
1) Each joint in pipeline changes a joint gap due to the earthquake, but the mean value of them hardly shifts.
2) Initial gap or bending of joint hardly influences the seismic behavior.
3) The change of joint gap caused by the earthquake is particularly large beside the bend pipe or the structure, comparing with in the straight line.
4) The safety factor of a curved joint including initial gap is larger than a straight joint beside bend pipe.View full abstractDownload PDF (1970K) -
Tomokazu HARAGUCHI, Osamu KATO, Akira TANAKA2007 Volume 2007 Issue 249 Pages 305-311
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSThe ability to purify water using carbonized waste biomass was examined. Two types of charcoal of thinned cedar and carbonized pine-needle were packed into each PVC column. Two types of charcoal of thinned cedar had different particle diameter of larger and smaller than 2 mm. Aqueous solution of potassium nitrate (KNO3) or water suspension with paddy soil passed through a carbonized material saturated with the test water. Increases of electrical conductivity and pH of a column with KNO3 solution were larger than those of a column with water suspension. Increase in concentration of total phosphorous was significantly larger for pine-needle than charcoals in the KNO3 solution experiment, and the concentration decreased for charcoals and kept constant for pine-needle in the water suspension experiment. For inorganic nitrogen, reduction by pine-needle was larger than charcoals. It was shown that carbonized pine-needle was more effective for the reduction of nitrate nitrogen than charcoal. Comparing the experiments using both test waters gave that the speed to be solved of soluble matter which was contained in a carbonized material was decreased in an experiment with water suspension because of the higher concentration of total dissolved matter and adherence of suspended matter.View full abstractDownload PDF (1051K) -
Anshun YOSHINAGA, Kazuhito SAKAI, Tamotsu NAKANDAKARI, Kazutoshi OSAWA ...2007 Volume 2007 Issue 249 Pages 313-318
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSThis study demonstrated the effectiveness of mulch composed of the Japanese pampas grass (Miscanthus sinensis) sheaves laid at the ends of furrows for preventing sediment runoff from cropland. The mulch was prepared by placing sheaves of Japanese pampas grass, I m in length and 15-20 cm in diameter, at the ends of furrows. The effectiveness of the mulch at preventing sediment runoff was assessed by measuring the amount of sediment in runoff water from two furrows, one with and the other without grass mulch, that were 15 m in length and 1 m wide. The findings revealed that the effectiveness of the mulch in reducing sediment runoff was 46%. Specifically, when the runoff sediment was sieved and classified by particle diameter, it was found that the effectiveness of mulch for the particle size of under 0.1 mm, the fraction is primarily responsible for high turbidity in coastal waters, was 30%. 95% of coarse sand with a grain size of 1 mm or larger was trapped by the mulch.View full abstractDownload PDF (2968K) -
Taiichi SAKUMA, Atsushi ISHII2007 Volume 2007 Issue 249 Pages 319-328
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSThis paper investigates support systems for the conservation of rice terraces by people in cities and village farmers in Kamogawa city, Chiba prefecture. Further, it clarifies the activities carried out by these people and farmers and highlights the pertinent issues. In Kamogawa city, the ownership and trust systems have been established for the purpose of conserving rice terraces in not only Ooyama-senmaida, famous for its rice terraces, but also the areas covered in the special zone for the conservation of rice terraces and Kamogawa Ecological Minded Kingdom. In all cases, there are many applicants from cities who would like to participate in agricultural works such as transplanting, harvesting and so on, because these areas are located near the big cities. However, there are not enough instructors in the form of village farmers who usually teach and instruct the participants on how to perform the agricultural work; thus, the areas adopting the ownership system or the trust system are considered to be small. In the case of Kamogawa Ecological Minded Kingdom, a private citizen spends several million yen annually to employ full-time instructors for the purpose of managing and conserving rice terraces. Other areas tend to maintain a balance among part-time instructors, village farmers, and their budgets; however, they fear that they might be unable to sustain such instruction in the future.View full abstractDownload PDF (1841K) -
Investigation from the comparative study of OH-ike and SHIDANOSHITA-ike irrigation pondsMasayuki FUJIHARA, Toshiko KAKIHARA, Kazuhiro TOMIOKA, Tadao FUKUSHIMA2007 Volume 2007 Issue 249 Pages 329-336
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSOH-ike irrigation pond in Kitaumemoto, Matusyama, is more eutrophic than SHIDANOSHITA-ike irrigation tank, whose volume is almost same as OH-ike, though inflow load of phosphorus of OH-ike is less than that of SHIDANOSHITA-ike. Since phosphorus was found out as limiting nutrient in OH-ike from the field observation, phosphorus flow through the tank was mainly investigated, using Vollenweider model. Application of Vollenweider model made it clear that the differences of physical condition (resident time and average water depth) and phosphorus settling rate caused the difference of eutrophic level. Since OH-ike is shallower than SHIDANOSHITA-ike, water in OH-ike is easy to mix vertically. Because of this, released phosphrus from the bottom of the pond under low DO concentration would be transported into euphotic zone and then used for phytoplankton production. In addition to that, irrigation water intake from the bottom of the pond makes stratification weak and that enhances the eutrophication.View full abstractDownload PDF (1351K) -
Masato NAKAMURA, Yoshito YUYAMA, Masaru YAMAOKA, Tomonori FUJIKAWA2007 Volume 2007 Issue 249 Pages 337-343
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSThe balance of materials in a biogas plant was estimated from the operating records of the plant and results of analysis of feedstock and products. Fertilizer characteristics of digested liquid and digested liquid supernatant produced as residues of methane fermentation were evaluated.
The results indicated that only 9.8% of C in the feedstock was converted into the C in CH4 during the methane fermentation process. The reason for this was that the feedstock, cattle manure slurry, contained much sawdust derived from bedding material. The biogas plant and livestock farmer need to cooperate to improve CH4 production efficiency. Digested liquid and digested liquid supernatant were considered to be readily available fertilizer because they contain large amounts of ammoniac nitrogen and potassium. Digested liquid supernatant is easier to handle because suspended solids are removed from the digested liquid.View full abstractDownload PDF (1159K) -
[in Japanese], [in Japanese]2007 Volume 2007 Issue 249 Pages 345-346
Published: June 25, 2007
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSDownload PDF (389K)
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