1987 Fiscal Year Final Research Report Summary
The characteristics of regional soils in Kyushu and Okinawa, and soil improvement
| Project/Area Number |
60302084
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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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 | Kyushu University |
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Principal Investigator |
TAKAYAMA Masateru Fac. of Agriculture, Kyushu University, Professor, 農学部, 教授 (60038312)
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| Co-Investigator(Kenkyū-buntansha) |
SHINJOU Toshiya Fac. of Agriculture, University of Ryukyus, Professor, 農学部, 教授 (40045109)
KUNITAKE Masato Fac. of Agriculture, Miyazaki University, Professor, 農学部, 教授 (10039323)
NANBA Naohiko Fac. of Agriculture, Kagoshima University, Professor, 農学部, 教授 (60041612)
KAKU Ken Fac. of Agriculture, Saga University, Professor, 農学部, 教授 (10038177)
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| Project Period (FY) |
1985 – 1987
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| Keywords | Ariake Clays / Decomposed Granite / Onjaku Soil, Shirasu / Kuroboku Soil / Special Soil / Soil Stabilization / 島尻層泥岩締固め / 土質改良 / 農地保全 |
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| Research Abstract |
The regional soils such as Ariake clays, decomposed granite, Onjaku soil, Shirasu, Kuroboku soil, Kunigami-maaji soil, and Shimajiri mudstone are distributed in Kyushu and Okinawa. These soils exhibit unusual geotechnical characteristics. The problems associated with these characteristics have arisen in the construction and preservation of soil structures, and soil conservation in agricultural field. In this research project the properties of these soils have been investigated, and the soil improvement procedure is presented. The following is the results obtained. 1.The soil improvement by addition of cement and lime to extra sensitive Ariake clays changes their properties into those similar to sands, resulting in an increase of shear strength. 2.Decomposed granite, Onjaku soil, and Kunigami-maaji soil have high natural water content and poor workability. The mechanical properties and erodibility of these soils can be improved by lowering the water content and increasing the density of the soils. 3.Onjaku and Kuroboku soil, which are not proper for filling materials, were mixed with decomposed sand stone and Shirasu. This procedure is effective to increase workability of the filling materials. 4.The long term stability of Shimajiri mud stone has been discussed in terms of the weathering effects on the mudstone softening. 5.Kunigami-maaji soil exhibiting high erodibility are widely distributed in Okinawa. High erodibility of this soil can be ascribed to the insufficient development of soil structure and low capability of water absorption and retention. 6.FEM programs to assess the stability of slopes in canal excavated in agricultural field heve been developed.
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