Nanjing mica sand is anisotropic because of its contents of flake grains. A series of drained tests for principal stress axes was fixed at 10°

30°

60°

80° were conducted with an automated hollow cylinder apparatus in Hong Kong University of Science and Technology

in order to study the inherent anisotropic characters of mica sand. During the tests

the coefficient of intermediate principal stress was fixed at 0.1

0.5 and 1.0

and the beginning density of sand was same. When the orientation angle of major principal stress changes from 0° to 90°

the shear strength of mica sands at first tends to reduce

reaches its minimum value at the orientation angle of 60°

and then increases gradually. The coefficient of intermediate principal stress has a great impact on the shear strength and deformation of anisotropic sands