シルト質土の締固め特性

Abstract

It is important for anyone engaging himself in the construction of some earth structures, such as earth dam, subgrade and base course of the road, to have a comprehensive knowledge respecting the relationship between the moisture content of remolded soils and their compacted density. From the viewpoint of engineering purposes, however, it is also necessary to know the influence of compacted densities which correspond to various moisture contents on the shear strength of the soil.So far, some investigations have been made with respect to physical properties of sandy soil or clay. As for silt whose particle size is situated between sand and clay, on the other hand, there exist many unknown parts in its engineering behavior.In this paper, some experimental considerations are treated for interesting characters encountered in compacting silty soil. Socalled Rhein-silt, a wind-laid deposit existing widely near the Rhein in Germany, is used as the specimen.The experimental research performed in this study consists of two procedures; one is the compaction test accompanied with measuring the penetration resistance of Proctor's needle, and another is the triaxial compression test of the compacted soil with pore pressure measurement.It is clarified from this study that there is a remarkable difference between the compaction curves (i.e. density vs. water content curves) obtained by either the wetting process or the drying one, and that the maximum shear strength of the compacted Rhein-silt exists at the water content somewhat smaller than the optimum, which corresponds to that of maximum negative pore pressure in the specimen.