| Project/Area Number |
06660296
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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 |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MIYAZAKI Tsuyoshi The University of Tokyo, Graduate School of Agriculture and Agricultural Life sciences, Dept. of Biological and Environmental Engineering, Associate Professor, 大学院・農学生命科学研究科, 助教授 (00209892)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
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| Keywords | Similarity / Scaling / Bulk density / Air Entry Value / Hydraulic Conductivity / Campbell's method / Kozeny-Carman / Cambell法 / コゼニ-カルマン法 / Campbell法 / Kozeny-Carman法 / 相似多孔質体モデル / Kozeny-Carmanの式 |
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| Research Abstract |
The bulk density of a soil changes with natural and artificial processes in a field. The larger the bulk density RHO_b of the soil, the larger the air entry suction h_e and the smaller the hydraulic conductivity K_s. Although both the Kozeny-Carman equation, based on Poiseuille's law, and Campbell's method, based on a similar media concept (SMC) by Miller and Miller (1956), are able to predict bulk density dependencies of hydraulic conductivities theoretically, the applicabilities and limitations of them have been vague. This study proposed a non-similar media concept (NSMC) model, composed of a characteristic length for the solid phase S,that for the pore phase d and a shape factor tau of the solid phase, to predict he and Ks values of a given soil as functions of its rho_b. By comparing the NSMC model with the Campbell method and the Kozeny-Carman equation, it was clarified experimentally that the NSMC model is applicable to aggregated soils in the predictions of he (rho_b) and Ks (rho_b) as well as to dispersed soils.
The applicability of NSMC model to sandy soil was sufficiently high. The applicability of this model to an aggregated woil depended upon the findings of an adequate shape factor tau^<**>. The tau^<**> value close to but a little larger tha rho_b/rho_s may give a rough estimation, but it is strongly recommended to measure the h_e-rho_b relation by which a reliable tau^<**> value is determined.
The NSMC model is a new and growing model. It was shown that the predictability of K_s as functions of rho_b of mechanically compacted clayy soils by the NSMC model were relatively poor. The NSMC model for such compacted soils may be improved by defining the shape factor as a function of the bulk density or compaction energy.
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