关键词: 离散元方法, 椭圆颗粒, 各向异性, 净砂, 双轴压缩试验

Abstract: Initial anisotropy caused by granular arrangement effects the mechanical behaviors of pure sand evidently. In order to study such effects, pure sand specimens consisting of elliptical particles at four different sedimentary angles (?) are prepared by the self-developed software NS2D firstly, and then biaxial compression tests are conducted on those DEM specimens. Secondly, the simulated results are compared with those of laboratory tests to validate this method. Finally, the influence of ? is studied by analyzing the simulated results. The results show that all of these four specimens show strain softening and shear dilation phenomenon. With the increase of ?, the strain softening phenomenon of stress-strain curve tends to become strain hardening, and shear dilation phenomenon becomes more and more unapparent. The peak and residual internal friction angles achieve the maximum when ? =0°. With the increase of ?, the peak internal friction angle decreases and then keeps constant, while the residual internal friction angle decreases. The initial principal direction of particle arrangement is parallel to the sedimentary direction. With the increase of axial strain, the principal direction of particle arrangement rotates to the direction parallel to the loading plane gradually, and the principal direction of contact rotates from perpendicular to sedimentary direction to perpendicular to the loading plane. And the increments of both rotations aforementioned increase with the increase of ?. The principal direction of strong contact force is perpendicular to the loading plane all the time.

Key words: discrete element method, elliptical particle, anisotropy, pure sand, biaxial compression test