1993 Fiscal Year Final Research Report Summary
Study on Time Dependence of Soil Pore Clogging in Slope Failure Mechanism
| Project/Area Number |
03806037
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
農業土木
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| Research Institution | Tokyo University of Agriculture and Technology |
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Principal Investigator |
YASUTOMI Rokuro Tokyo University of Agriculture and Technology, Department of Environmental Science and Resources, Professor, 農学部, 教授 (10011892)
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| Co-Investigator(Kenkyū-buntansha) |
MIHARA Machito Tokyo University of Agriculture, Department of Agricultural Engineering, Researc, 農学部, 助手 (00256645)
KATO Makoto Tokyo University of Agriculture and Technology, Department of Environmental Scie, 農学部, 助手 (50015096)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Agriculturtal Land Conservation / Levee Slope / Soil Permeability / Pore Clogging / Internal Erosion |
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| Research Abstract |
Erosion disasters occurred on agricultural lands and facilities as a result of heavy rainfall in Yasaka area. Slope failure or gully erosion of paddy field levees was most common. Soil permeability in toe of levee slope in non-consolidated paddy field was lower than that in top of levee slope. Clay percentage of samples soils in toe of levee slope was higher than that in top of levee slope. Observations of soil pores with a polarized microscope showed the sedimentation of clay particles around soil pores in toe of levee slope. It was concluded that transportation of clay particles produced soil structural changes in levee slope. As soil water pressure and degree of saturation increase easily in heterogeneous slopes, protection measures should be considered to prevent slope failure.
Percolation volume of soil suspension through porous mediums per unit time decreased against the increase in the volume concentration. The changes in percolation volume per unit time were analyzed using the Backingham-Reiner equation. The conclusion was that the radius of plug flow should be a least smaller than that of pores to prevent the immediate clogging by soil suspension flow.
Pipe drainage we an effective protection measure of heterogeneous slopes. It was suggested that effective strainer structure of under drain pipes in which pore radius of strainers enlarged according to flow direction was designed from rheological properties of soil suspension flow which prevented the immediate clogging. Research of strainer structure of under drain pipes which keeps constant drain-age discharge is significant for slope protection.
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