Abstract:

Scanning electron microscope (SEM) was used to observe microstructure of soft clay before and after shearing under complex stress path, which analyzed microscopic nature on anisotropy of normalized shear strength of intact soft clay in three respects including changing characteristics of pore arrangement, changing characteristics of pore pattern and changing characteristics of pore scale. Test results revealed that the pore arrangement was disorder before and after shearing, and changes of pore orientation were very small, which influenced very little on macroscopic properties of clay. Changing characteristics of pore pattern contributed significantly to anisotropy of normalized shear strength of clay in coefficient of intermediate principal stress equal to 0. Changing characteristics of pore scale contributed significantly to anisotropy of normalized shear strength of clay in coefficient of intermediate principal stress equal to 0.5. Therefore, the micro-change factors which influenced anisotropy of normalized shear strength of clay after shearing were different in different coefficients of intermediate principal stress.

Key words: microstructure of soil, anisotropy, coefficient of intermediate principal stress, normalized shear strength