A meso-scale study of the influence of particle shape on shear deformation of coarse-grained soil

Particle shape is one of the main factors that affect the compactness, mechanics and seepage of coarse-grained soil. In order to analyze the influence of particle shape on the shear characteristics of coarse-grained soil, the discrete element method is used to generate four different particle groups. The direct shear test simulation and macro-micro shear response research of coarse-grained soil are carried out. The influence of particle shape on shear stress-shear displacement and volume strain-shear displacement is obtained. The shear stress, strain characteristics and dilatancy characteristics of coarse-grained soil are analyzed. The influence of particle shape on coarse-grained soil on macro-micro scale is studied by analyzing the evolution law of macro-micro parameters such as shear zone thickness, particle rotation value, average contact number, porosity and contact force system. The results show that the self-locking effect of the special-shaped particles is greater than that of the pure round particles, and the shear strength of the sample tends to increase with the decreasing shape coefficient. The sample particles move under the action of external load, and the strain is mainly shown in the shear zone where the particles move violently and dilate greatly. The particle shape coefficient decreases, the initial average contact number of the sample increases, the internal friction angle "φ" increases, and the larger the increment of porosity in the shear band, the larger the dilatancy amplitude. During the shearing process, the strong chain gathers in the shearing zone and acts as a skeleton. With the decrease in the shape coefficient, the percentage of the force chain length in the range of 0 - 5 increases. The number of strong chains in the shear band increases with the decrease in the shape coefficient, and the peak value content ranges between 30% and 35%.