MECHANICAL PROPERTIES OF SATURATED COHESIVE SOIL WITH
SHEAR HISTORY UNDER THREE DIMENSIONAL STRESS CONDITIONS

HIROFUMI TOYOTA, NAOKI SAKAl and KOUICHI NAKAMURA

ABSTRACT : There are many cases in which ground is subjected to stress history not only via artificial actions but also by tectonic movement. The effects of stress history under three dimensional stress conditions are one of the important phenomena which have to be evaluated for the accurate prediction of ground deformation. The purpose of this study is to supply the fundamental data relating to stress history which can be incorporated in prediction or design techniques. To achieve this objective, a series of hollow-cylindrical torsional shear tests was conducted on saturated cohesive specimens which were subjected to shear history under constant p' , various directions and three dimensional stress conditions.
    From the experimental results, it was seen that the magnitude of the ultimate strength was the same for a given p' and not related to the shear history. On the other hand, the deformation characteristics (the elastic locus) behaved differently with respect to the shear history. The elastic locus developed by the stress history has directional and stress condition effects.
    Finally, taking into account the experimental results of the present study, the predominant parameters -- the difference in the direction of shear, and the stress condition between the shear history and the shear -- were selected. Using these parameters, the elastic boundary space due to the stress history was confirmed to evaluate the effects of the shear history under three dimensional stress conditions.

Key Words : anisotropy, consolidated drained shear, stress history, stress-strain relation, torsional shear (IGC: D6)