COMPRESSIVE AND SHEAR CHARACTERISTICS OF UNDISTURBED DECOMPOSED GRANITE SOILS PAYING ATTENTION TO THE DEGREES OF WEATHERING

In order to investigate the compressive and shear characteristics of undisturbed Hiroshima type decomposed granite soils, the isotropic compression and triaxial compression tests were carried out using the undisturbed specimens made up by the new core bit. Test results were discussed paying attention to the degrees of weathering of samples.The results obtained can be summaraized as follows.1) The irreversible change of void ratio under isotropic compression is due to the particle breakage and the vanishing of structure effect.2) The stress-strain behavior, stress-dilatancy relation and shear constant φ' depend on the degrees of weathering.3) Failure criterion is expressed in terms of coefficient of the exponent.4) The decrease in strength due to submergence is remarkable in a low confining pressure and in moderately weathered sample.