Takahiro Yamanashi

Shear Modulus and Damping Ratio for Normally Consolidated Peat and Organic Clay in Hokkaido Area

This paper presents that the shear modulus at small strain (G0) for peat and organic clay in normally consolidated state, as well as the strain dependence of the shear modulus and the damping ratio (dynamic property). In analyzing dynamic ground behavior, G0 and dynamic property of soils should be accurately determined. Therefore, eight types of peat and two types of organic clay, which were all different in terms of engineering property, were given a series of cyclic torsional shear tests in the normally consolidated state, to clarify effects of physical properties of the soils and effective confining pressure on G0 and dynamic properties. Finally, based on the test results, empirical equations to determine G0 and dynamic property of peat and organic clay are proposed.

Land-Improvement Technology Using the Heat of Soil Stabilizer Reactions in Cold Regions

Laboratory tests on small soil specimens under cold weather conditions found that curing temperature significantly influenced the strength of unsuitable soil improved by adding a stabilizer. The improved soil was found to develop little strength when the ambient temperature was below 0°C. However, the authors considered that the temperature inside a full-scale embankment might not decrease as much as in the small specimens in the laboratory tests because the ambient temperature is expected to have a smaller effect on the soils in the full-scale embankment than on the small soil specimens. In this study, they conducted a field experiment to investigate the extent of freezing and the strength improvement of soils that have been modified with stabilizers. In addition, they measured the effects of a quicklime-mixed soil blanket placed on the constructed embankment. The field experiment confirmed that the embankment underwent little freezing while the soil was developing strength.