Study on mechanical properties of sand-silt mixtures based on discrete element method simulations
In view that the mechanical properties of silt-sand soil are significantly affected by fine content,the silt-sand soils are equivalent to binary mixtures formed by coarse and fine particles,and discrete element method simulations of drained triaxial tests are conducted.The influence of fine content on the initial packing state,peak strength and residual strength of the silt-sand binary mixtures and the corresponding mechanical mechanisms are analyzed from both the macro-and micro-scales.The simulation results show that the initial stacking state and the related mechanical properties of the binary mixtures evolve from coarse-dominant to fine-dominant around the threshold fine content of about 40％,with the micro-structure changing from fine particles filling the void of coarse particles to coarse particles floating in the fine particles.The peak strength of binary mixtures shows an increasing and then decreasing trend with the increase of fine content,while the residual strength is less affected by fine content.For binary mixtures with fine content of less than 60％,complex particle interactions and stress redistribution exist between coarse and fine particles with the increase of shear strain.Whereas for binary mixtures with fine content larger than 60％,the contact stress redistribution between particles is relatively weak due to the dominant role of the fine particles in the force chains.
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