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53 巻, 1 号
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その枠組みと砂防対策事業への応用古谷 尊彦2000 年 53 巻 1 号 p. 1-2
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーPDF形式でダウンロード (2593K) -
市房山崩壊地群を例として戎 信宏, 村瀬 悠, 丸谷 知己2000 年 53 巻 1 号 p. 3-9
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーThe distribution, size and change of landslides are mainly investigated by aerial photographs and field survey, though it takes much labor if a wide range of landslides is measured. An alternative approach is to use satellite remote sensing. A purpose of this study is to map and monitor landslide areas at Mt. Ichifusa in Kyushu using remote sensing data of Landsat and SPOT images. The results are as follows :
1) The accuracy of classification of the landslide is over about 71% using NDVI from Landsat and SPOT data. The total area of the landslide estimated from TM and HRV XS data is nearly the same as that mapped by using aerial photographs.
2) A different sensor and different day of observation on Landsat and SPOT cause the change of NDVI values for the classification and each time NDVI values change, the ortho photograph of ground truth data is required to esti-mated classification. This is a problem in monitoring the landslide areas by satellite data for a long term.
3) Computing shadow and stream areas from DEM by Geographical Survey Institute data using GIS (Geographic Information System) increases the accuracy of classification of the landslide areas.
4) Using satellite remote sensing data that have the ground resolution appropriately selected to the size of the land-slide leads to high accuracy of classification of the landslide areas. At mountainous areas it is more important to use satellite data in for shadowless period than to use high ground resolution data.抄録全体を表示PDF形式でダウンロード (11513K) -
小田 晃, 水山 高久, 阿部 彦七2000 年 53 巻 1 号 p. 10-18
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーIn general, sabo facilities are arranged to control sediment directly at the cross section of river. Such facilities disturb flow, sediment transport and passing of fish. From the side of environment, it is necessary to control sediment transport indirectly without cross structures at the flood period.
In this study, the side weir arranged to decrease the discharge at the main channel for the indirectly sediment control. And deposition of sand is expected at the main channel by the decrease of discharge at the main channel. The discharge from the side weir passes through the bypass. Possibility of the indirectly sediment control is showed from the hydraulic experiment and the numerical computation of two-dimensional bed-level variation.
The experiment and the numerical computation were carried out under several cases. The side weir length, height, channel width and discharge were varied to understand the effect of the diversion flow on sand deposit. The relation of discharge and sand volume between the main channel and the bypass were showed by the experiment. The time variation of cross section profile and velocity vectors around the side weir was showed by the numerical computation.
As a result, the influence of the side weir length upon outflow sand from main channel was shown. Sand deposit at the main channel was confirmed from the experiment and the numerical computation. Main deposition area is the sec-tion of side weir on the border of bypass. And possibility of the indirectly sediment control without cross structures was suggested.抄録全体を表示PDF形式でダウンロード (8452K) -
水野 秀明, 南 哲行, 水山 高久2000 年 53 巻 1 号 p. 19-25
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーAn open type steel dam is a good facility in capturing debris flow for it can prevent the loss of the trapping capacity. In planning for the arrangement of countermeasures in such a basin where has a large amount of sediment discharge, a series of open type dams will be constructed. The arrangement has the following effects; 1)an increase in the reduction rates of peak sediment discharge and total sediment discharge, 2)adecrease in the sediment concentration. In order to confirm these functions, we conducted two cases of experiments-one was using one dam model and another was using two dam models. Three types of dam models (L/d95=3.5(type-1), 2.5 (type-2) and 1.9 (type-3) ) were used, where L represents the distance between steel pipes and d95 represents 95 weight percent grain size. An experimental flume that has a width of 20cm, height of 40cm and length of 500cm, was set at 17 degrees. Water was supplied at 2.0l/sec. Results show that in cases where two dam models were arranged-especially arranged type-2 at downstream, the reduction rates were found to be higher than the cases of using one dam model. Sediment concentrations of the cases of using two dam models were lower than the latter case. In cases of using two dam models of type-2, however, the reduction rates were lower and the sediment concentrations of the case was higher than in the case of using one dam model of type-2.抄録全体を表示PDF形式でダウンロード (7071K) -
萩原 弘, 大田原 幸亘, 白山 昌義, 中濃 耕司2000 年 53 巻 1 号 p. 26-34
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーThe Sabo-CSG Method (provisional name) is a method of constructing structures by mixing cement with unproc-essed bed material obtained near the site. It is executed similarly to the CSG method and INSEM method, but these are methods of improving sand and gravel. With this method, the materials are mixed based on the same concept as concrete.
This report is a detailed explanation of the design of the standard mix proportion and the results of a verification of the method in the field using general purpose construction machinery. The following summarizes the findings.
1) Laboratory experiments show that it is necessary to reduce fluctuations of the quantity of water per unit volume of sabo-CSG material (during the mixing of the materials) in order to obtain the required consistency and compres-sive strength.
2) A consistency with a VC value between 5 and 10 seconds is appropriate for the use of a compact vibrating roller.
3) It is possible to use a simple mixing method employing an agitator-body truck.
4) It is counted on to reduce construction costs to a level lower than that of concrete.抄録全体を表示PDF形式でダウンロード (14419K) -
高橋 透, 松岡 充宏, 瀬尾 克美, 荒木 義則, 古川 浩平, 水山 高久2000 年 53 巻 1 号 p. 35-46
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーIt is important to predict occurring place and time of debris flow by the way of researching rainfall and morphological data. This study was carried out on the basis of investigation of hazard literature and inquiry of them to the competent firehouse, etc. Forecast model of debris flow's occurrence was created by the method of multiple discriminant analysis of geographical and rainfall factors. This model could give an effective warning and evacuation line for every debris flow with occurring potential in hazardous torrents. As a result of this research, it was shown that the precision of the predict of debris flow's occurrence by this method was higher than the standard one by only rainfall factor.抄録全体を表示PDF形式でダウンロード (8105K) -
杉浦 信男, 仲野 公章, 小林 幹男, 葛西 勝栄, 安養寺 信夫2000 年 53 巻 1 号 p. 47-51_2
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーThe phreatomagmatic eruptions of Usu Volcano began from vents of the western flank of Mount Nishiyama on March 31, 2000. In the next day, April l, another phreatomagmatic eruptions began from vents of the western flank of Mount Konpira. In order to assess the risk of eruption-induced sediment disasters, the Team of Experts for the Sediment Disaster has surveyed the state of the volcanic ash deposits, the devastation of torrents, and the damage of erosion control dams. The results of the surveys from April 1 to 11 are as follows. 1) Volcanic ash deposits near the vents was observed as 50 cm-1m thick, but that at the outside of the evacuation ordered area was very thin(thinner than 1mm) 2) Hot mudflows occurred mainly firom the vents of the western flank of Mount Konpira. The repeated hot mudflows fulfilled the erosion control dams of the Nishiyama River and then flooded into the Toya Spa Town. Two bridges were washed away. The depth of the hot mudflow deposits was observed very thin, but locally 1.5-2.5m thick at maximum. 3) Thick ash deposits and severe land deformation yield a large amount of unstable sediments in the upper reach of the Itaya River.抄録全体を表示PDF形式でダウンロード (22118K) -
牛山 素行, 北澤 秋司, 斎藤 彰朗2000 年 53 巻 1 号 p. 52-55
発行日: 2000/05/15
公開日: 2010/04/30
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石井 靖雄, 小山内 信智, 岩波 英行2000 年 53 巻 1 号 p. 56-58
発行日: 2000/05/15
公開日: 2010/04/30
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田畑 茂清, 水山 高久, 井上 公夫, 杉山 実2000 年 53 巻 1 号 p. 59-70
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーHietu Earthquake of M 7.0-7.1 induced a large landslide so called as Tombi landslide on Mt. Tombi in the up-stream area of the Jouganji River in central Japan, on April 9, 1858. This study examines all the available informationon the Tombi landslide, especially its volume and movement, in order to make the whole aspect as clear as possible.
According to old documents, two peaks called as Oh (large)-Tombi and Ko (small)-Tombi collapsed and the land-slide debris dammed up mountain valleys to form two large lakes. The landslide dams then failed on April 23 after 14days, and a mud or debris flow rushed down along the Jouganji valley into the Jouganji fan. A mud or debris flow oc-curred again on June 7 after 59 days. The Tombi landslide scarp is composed of massive andesite lava on granodioritebase, which the uppermost part is fragile, and this geological setting was apparently one of the important causativefactors for the slope failure with the shock of the earthquake. The fades of the landslide debris indicated that a rapiddebris avalanche occurred.
The volume of landslide debris was estimated as 1.27×108m3 from the distribution of remaining debris in the valley.The landform of Oh-Tombi and Ko-Tombi before the landslide was supposed referring to old document and drawings.The volume of landslide mass was estimated by comparing the old landform with the present landform. The result ofvolume 1.14×108m3 corresponds well with the estimated volume of depositions.抄録全体を表示PDF形式でダウンロード (16808K) -
木佐木 一2000 年 53 巻 1 号 p. 71-75
発行日: 2000/05/15
公開日: 2010/04/30
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嶋 丈示2000 年 53 巻 1 号 p. 76-79
発行日: 2000/05/15
公開日: 2010/04/30
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大村 寛2000 年 53 巻 1 号 p. 87-87_1
発行日: 2000/05/15
公開日: 2010/04/30
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三好 岩生2000 年 53 巻 1 号 p. 90-91
発行日: 2000/05/15
公開日: 2010/04/30
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2000 年 53 巻 1 号 p. 101
発行日: 2000/05/15
公開日: 2010/04/30
ジャーナル フリーPDF形式でダウンロード (91K)
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