Abstract
In the southern part of the Gifu Prefecture, especially around Kagamihara city, there distribute the black soil, a kind of the organic soils, that is called the Kuroboku soil of Kagamihara or the Kagamihara Kuroboku soil. The author and his coworker studied experimentally the physical properties of this soil.
The results are summarized as follows;
(1) This soil is rich in organic matter contents, has a high moisture holding capacity, and is acidic due to proceeded humification.
(2) The principal clay minerals are 14A° minerals and Kaolin minerals, in contrast with the typical volcanic ash soils containing allophane as the principal component.
3) Once disturbed the soil showed a great decrease in the unconfined strength and the permeability because of its high seneitivity.
(4) The samples subjected to the drying experiences change their dynamic properties; the chang is irreversible.
(5) It is found that the over consolidation can effectively lengthen the stress relaxation time; this feature is useful in practice.
(6) The Kagamihara Kuroboku is, in general, inadequate as aworking material; however, the soil stabilization by the use of the chemical agents, i. e. adding Ca (OH)2 and auxiliary agent Ca (HPO4)2+2(CaSO4·2H2O), is very effective in improving its strength.
