Fabric analysis of two-dimensional tests for coarse-grained soils

The fabric of coarse-grained soils primarily refers to the arrangement of soil particles,and it is the kernel factor for mechanical properties of coarse-grained soils.Two-dimensional tests were conducted in order to study the influence of fabric on stress-strain relationship of coarse-grained soils.The model test images are analyzed by a computer image measuring system,and the particle displacement,rotational angle,long axis orientation,coordination number and branch vector are analyzed quantitatively through the system.The calculated results show the particle movement of two-dimensional tests has the same law as that of triaxial tests,which means the model tests can reflect the process of triaxial tests.The vector graphs of particle displacement and particle dislocation indicate that the macro-strain originates from particle adjustment,particle dislocation occurs at different deformation stages,the number of particle dislocation increases with deformation development,and finally the particle dislocation concentrates on shear band.The orientation of particle long axis and branch vector have good relationship with the deviator stress,and the stress increases with orientation enhancement,and the stress attenuates with orientation decrease.The change of the average branch length is unnoticeable with deformation development for intimately contacted particles.The average coordination number is not in good agreement with the volumetric strain,which is probably related to polygon particles and large particles.