关键词: 原状饱和软黏土, 门槛循环应力比, 循环耦合剪切试验, 循环扭剪试验, 三向非均等固结

Abstract:

The soil static and dynamic universal triaxial and torsional shear apparatus facilized in Dalian University of Technology was employed to perform different types of experimental test of undisturbed saturated soft marine clay in the yangtze estuary. The samples were subjected to undrained cyclic vertical and torsional coupling shear and cyclic torsional shear under three-directional anisotropic consolidation conditions with different initial consolidation parameters. The effects of initial orientation angle of maximum principal stress, initial ratio of deviatoric stress , initial coefficient of intermediate principal stress and stress mode of cyclic shear on the threshold cyclic stress ratio were investigated. It is found that the effects of initial orientation angle of maximum principal stress and initial ratio of deviatoric stress on the threshold cyclic stress ratio are remarkable under three-directional anisotropic consolidation; the threshold cyclic stress ratio decreases obviously with increasing initial orientation angle of maximum principal stress and initial ratio of deviatoric stress. However, the initial coefficient of intermediate principal stress has almost no effect on the threshold cyclic stress ratio. It is also shown that the stress mode of cyclic shear has significant effect on the threshold cyclic stress ratio; the values of the threshold cyclic stress ratio determined by the cyclic vertical and torsional coupling shear tests are smaller than those determined by the cyclic torsional shear tests.

Key words: undisturbed saturated soft clay, threshold cyclic stress ratio, cyclic coupling shear test, cyclic torsional shear test, three-directional anisotropic consolidation