Effects of grain size distribution characteristics on compaction and deformation-strength characteristics of gravelly fill materials

It involves many difficulties to employ a large-scale triaxial apparatus in an attempt to manifest deformation and strength characteristics of coarse-grained soil. Instead, the deformation and strength characteristics of in-situ coarse-grained soil may be estimated based on the results of the shear test using a smaller-sized specimen whose grain size distribution is adjusted being compatible with the specimen size in the laboratory. In the current practice in Japan, the degree of compaction Dcis usually employed in use for the density control, hence implicitly the strength control, for the embankment construction. On the other hand, the compaction curve of such a smaller-sized sample is likely different from that of the original fill material comprising much larger grains. Therefore, the compaction and shear characteristics of both the original and the grain-size adjusted samples should be manifested in order to estimate the strength of in-situ embankment. In this paper, the effects of grain size distribution on compaction as well as the deformation-strength characteristics were examined in a series of drained triaxial compression test, in which two types of coarse grained fill materials (i.e., angular- and round-shaped gravels) were tested.