定轴排水剪切试验中各向异性砂土的力学响应

南京云母砂主要由片状颗粒组成，具有较为明显的各向异性特性。采用香港科技大学的自动控制空心圆柱扭剪仪进行了应力主轴方向角分别为10°、30°、60°、80°的密实云母砂定轴剪切试验，研究云母砂的初始各向异性规律。为研究中主应力的影响，又对同一密度的试样在中主应力系数b＝0.1、0.5、1.0三种不同情况下进行定轴剪切试验。试验结果表明，在大主应力方向角从0°～90°的变化过程中，强度先减小后增大，且随着b值的增加强度增大；变形表现出明显的各向异性，随着b值的增加体变增大

Behavior of anisotropic mica sand under fixed principal stress axes drained shear test

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