Effects of intermediate principal stress parameter on deformation behavior of sands under cyclic rotation of principal stress axes

Four series of drained tests for the intermediate principal stress parameter b=0.1,0.5 and 1.0 in each series under the condition of cyclic rotation of the principal stress axes are conducted on Toyoura standard sand with an automated hollow cylinder apparatus at Hong Kong University of Science and Technology.The test condition is that only the principal stress axes rotated cyclically from 0°to 180° relative to the vertical while the magnitudes of the effective principal stresses kept constant.The experimental results indicate that the intermediate principal stress parameter b has great effect on the deformation behavior of sand under the cyclic rotation of the principal stress axes.And its effects on the development of strain components and the volumetric strain,the relation between shear stress and shear strain components and the flow rule of sand under the cyclic rotation of the principal stress axes are studied.