Analysis on Evolution of Force Chain and Contact Network of Non-Cohesive Soil

A biaxial test model was established based on the discrete element method to simulate the microscopic evolution of non-viscous soil upon loading. The shear strain, deviator stress and volumetric strain of the samples at different time steps were recorded, the evolution process of the force chain in the samples was observed, and the average degree (coordination number), 3-cycle and average clustering coefficient over force-chain particles were also analyzed respectively from the perspective of complex network. The following analysis results are obtained. The larger the value of inter-particle friction coefficient, the higher the peak value of shear stress, and the more obvious the strain softening phenomenon. The force chains in the samples with higher inter-particle friction coefficient tend to be more vulnerable to damage during loading. In the loading process, the average degree first increases, then decreases and finally tends to be stable. The value of average degree increases with the increase of confining pressure, and decreases with the increase of friction coefficient. The clustering coefficient of the particles within the force-chain particles is linearly related to the average length of the force chains at critical state.