| Project/Area Number |
62560224
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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 | Hokkaido University |
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Principal Investigator |
YAZAWA Masao Hokkaido University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (30001473)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Unsaturated soil / Soil compaction / Soil structure / Pore component / One-dimensional compression test / Compression load / Compacted soil / コ-ン指数 / 土壌の圧縮 / 圧縮試験 / 飽和土 / e〜logP曲線 / 透水係数 / 乾燥密度 / コーン指数 |
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| Research Abstract |
In 1987, one-dimensional compression test of undisturbed soil samples from field soils was done under very wet condition. The soil structural changes due to compaction was evaluated by the measurement of shrinkage behaviors of compacted soils. The changes of physical properties (permeability and water retentivity) due to compaction could be explained by the changes of structural pore contents as the structural index.
Modern mechanized farming is creating over-compaction of field soils. The aim of this study is to clarify the soil structural changes due to compaction.
In 1988, the structural state of soils compacted at different molding water contents by Proctor compacting-apparatus was evaluated. The structural pore content of soils compacted under high molding water content ranges was very poor, and it showed an abrupt increase at just a little lower content than high water ranges. The water content showing an abrupt increase of structural pore seemed to be closely related with the changes of aggregate strength due to drying.
In 1989, one-dimensional compression test for the soil layers just after tillage was done. The structural macro pore of compacted soils was high under the water contents corresponding to plastic limit or shrinkage limit of each soil. From the results of compression test for soil layers of 30 cm in length, it was clarified that the increase of dry density exerts the depth of 20 to 25 cm under 2kgf/cm^2.
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