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論文(リポジトリ) |
論文(リポジトリ)
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高濱, 信行 ; 古川, 昭夫 ; 周, 亜明
概要:
The Three Gorges Dam, which is one of the biggest construction projects during this Century in the world, is being const
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ructed at Sandonpong in the middle reaches of the Yangtze River. Many landslides (in a broad sense, including slope failure and rock fall) are distributed along the both banks of the dam reservoir. Sediment accumulation and reactivation of ancient landslides in the dam reservoir have become big problems to this big project. Investigation by the authors on Sept. 2004, focused on two subjects: 1) problems of reactivation of ancient landslides and 2) the problems of foundation of new constructed towns along the dam reservoir. The Jipazi landslide occurred on July 17, 1982, on the Ieft bank of the Yangtze River, about 1 km east of Yunyang Town. The slid mass of about 1.8 million cubic meters of volume, rushed into the River. It was a partial reactivation at the west side of the ancient Baota landside. Moreover, the reactivated small slide blocks, which occurred at the same time in 1982, were described in the engineering geological map of the Baota landslide. We observed several small-scale landslide cracks in the upper part of the ancient Baota landslide. It suggests that, the ancient Baota landslide might be in an “active stage” as a whole. Hence, the detailed geological investigation of the ancient Baota landslide and observation of the present slide movement are very important subject. We found that the geology of new Fenjie and Wushan towns are composed of semiconsolidated ancient landslide materials, e.g. landslide debris, landside blocks and mudflow deposits. The materials are very permeable and brittle as a mass. Detailed geological survey and observation of displacement, deformation and groundwater measurements are principal subjects.
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| 2.
論文(リポジトリ) |
論文(リポジトリ)
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高浜, 信行 ; 古川, 昭夫
概要:
The Three Gorges Dam, which is one of the biggest projects this Century in the world, is being constructed at Sandonpong in the middle reaches of the Yangtze River. The authors observed many ancient mega (to gigantic) landslides (in the
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broad sense, including slope failure and rock fall) along the both banks of the dam reservoir. Three Gorges, namely Qutang, Wu and Xiling Gorges, are composed of landslide blocks and their topography, is famous as one of the attractive spots of the Yangtze River cruise. Geology of the reservoir area is mainly composed of the Paleozoic-Mesozoic stratified sedimentary rocks, and that explains the geologic structure and mass-moved deformed structure which can be observed clearly. At the immediate upper stream of the Three Gorges, we can observe a horizontally stratified semi-consolidated silty layer about 20 meters thick, which made up the fluvial terrace-like morphology. It seems that the Pleistocene sediment was deposited in a stagnant water area and it suggests the existence of an ancient natural landslide-dam downstream. Furthermore, the basement geology of the Fenjie City and Baidicheng Town are composed of ancient landslide debris deposits. Sediment accumulation and reactivation of ancient landslides in the Three Gorges Dam reservoir are very difficult problems for this big project. There is some high potentiality that the ancient mass movement deposits distributed along both sides of the Yangtze River, will trigger reactivated landslides with the storage of water. The detailed investigation of ancient landslides is an important subject for this big project.
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| 3.
論文(リポジトリ) |
論文(リポジトリ)
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佐藤, 修 ; 青木, 滋 ; 鈴木, 幸治 ; 仲川, 隆夫 ; 橋本, 哲夫
概要:
Some spring water (50 samples) was collected from the landslide areas in the Chanjiang (Yantse) valley, and river water was sampled from the Chanjiang river and its branches. Two rain water samples (Nov. 2, 1987) were collected in Huepai
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district. The conventional measurements of low level tritium were carried out by using liquid scintillation counting. Spring water varied from 0.22 to 6.73 Bq/l (mean value 3.09+1.18 Bq/l). and the Changjiang river water varies from 3.40 to 3.81 (Mean value 3.7+0.81 Bq/l).The rain water was 0.63 and 1.78 Bq/l. Water source of the rain water in this season was estimated as sea water after consideration of climatic conditions and the tritium concentration of sea water. Some ground water having high tritium concentrations was affected by precipitation contaminated by atmospheric nuclear explosion tests and a few low tritium concentration water was surely recharged before the artificial tritium addition. We concluded that the conventional measurements of low level tritium concentrations is very useful to estimate the ground water flow in the landslides in China.
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| 4.
論文(リポジトリ) |
論文(リポジトリ)
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佐藤, 修 ; 青木, 滋 ; 鈴木, 幸治
概要:
Groundwater samples, river water and rain water for chemical analysis were collected from landslide areas in the Changjiang valley during autumn of 1987. Electrolite concentrations of groundwater from the landslide area was higher
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than from that of the Changjiang river water. The main constituents of groundwater was alkaline earth hydrogencarbonate in many samples reflecting the geology of the investigation area. Sulfate and chloride ions were minor constituents. The existence of those minor ions indicates that the some spring water in the landslide originated from the deep groundwater in the investigation area.
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