Abstract: The macro-mechanical properties of coarse-grained soils depend on its initial fabric and fabric variation in deformation process. Specimens of different initial fabric structures were prepared and two-dimensional parallel tests were conducted to investigate the influence of fabric on stress-strain relationship of coarse-grained soils. Particle movement was measured by computer image measure system, and fabric change in deformation process of coarse-grained soils was evaluated. Results show that (1) the stress-strain curves of parallel tests were different, which means fabric plays an important role in stress-strain relationship; (2) the orientations of branch vector and particle’s long axis enhanced with the increase of stress in the shear process before failure happened; (3) the peak deviatoric stresses increased with the increase of principal values of initial fabric; (4) the average branch length decreased slightly with the increasing of volumetric strain; (5) the average coordination number did not increase with the diminish of void ratio, which was probably related with polygon particles and big particles in small numbers.

Key words: coarse-grained soils, stress-strain relationship, fabric, branch vector, coordination number, particle’s long axis, triaxial tests