ANISOTROPY IN MECHANICAL PROPERTIES AND ITS SIMULATION OF SANDS SAMPLED FROM NATURAL DEPOSITS

Abstract

A series of static triaxial compression and extension tests and cyclic undrained triaxial tests on the undisturbed specimens obtained by the in-situ block sampling method were performed to assess the anisotropy in the static and cyclic deformation-strength characteristics of naturally deposited sands. Test results showed that anisotropic mechanical properties can be observed clearly not only in artificially deposited sands, but also in naturally deposited sands. It was recognized that mechanical anisotropy of natural cohesionless soils examined in the present study is characterized by the phenomena in which sand is more compressible and less extensible in the horizontal direction than in the vertical direction of the in-situ sand grounds and is attributed to the fabric anisotropy formed by the parallel alignments of sand particles induced during their depositing process. Moreover, it was also indicated that the anisotropic stress-strain-dilatancy properties and liquefaction characteristics of naturally deposited sands which contain the least amount of finer fractions could be simulated to a certain degree in a laboratory by adopting the sand sample preparation method such as pluviation of sand through air and MSP methods described in the previous paper (Miura and Toki, 1982).