1997 Fiscal Year Final Research Report Summary
Formation of sedimentary structures in flume experiments under upper-flow-regime conditions
| Project/Area Number |
08640565
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | Department of Geoiogy, Faculty of Education, Iwate University. |
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Principal Investigator |
YAGISHITA Koji Iwate University, Department of Geology, Faculty of Education Professor, 教育学部, 教授 (90239731)
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| Co-Investigator(Kenkyū-buntansha) |
ASHI Jyuichiro University of Tokyo, Graduate School, Institute of Geoscience Assistant Professo, 大学院・理学研究科, 助手 (40251409)
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| Project Period (FY) |
1996 – 1997
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| Keywords | plane beds / flume experiments / upper-flow-regime / imbrication / detrital grains / Froude Number / ripples / low-relief bedform / formational process / critical flow. |
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| Research Abstract |
In an attempt to produce plane beds under upper-flow-regime conditions, we have conducted a number of runs (experiments) using a hydraulic flume of 15 cm wide and 700 cm long, at the Ocean Research Institute, University of Tokyo. We have succeeeded in producing two types of plane beds : 1) laminae formed and buried by the migration of low-relief asymmetric ripples under near- or sub-critical flow (Froude Number Fr=0.94 ; type 1), and 2) laminae formed without causing any low-relief bedform but under super-critical flow (Fr=1.98 ; type 2). After making these two types of plane beds, imbrication of detrital grains along each plane bed was investigated. The sediments of sand-sized quartz grains (mean diameter 0.72 mm) show a high angle of imbrication (up to 30ﾟ) in type 2, whereas very low angle of imbrication (close to 0ﾟ) in type 1. Differences of imbrication angle between the two types of plane bed may be useful to infer the individual formational process of plane beds that are observed in the field.
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