Size Effect and Macro-Microscopic Bearing Characteristics of Compressed Shallow Foundations Based on Discrete Element Method and Centrifugal Similarity Principle

Based on the discrete element method and the centrifugal similarity theory, Particle Flow Code PFC2D was employed to establish numerical models of soil for compressed shallow foundations. The particle size effect and boundary effect of soil-bearing capacity for compressed shallow foundations, as well as the microscopic characteristics and failure mechanisms of soil, were studied. The results show that when the ratio of the foundation width to the maximum particle size in the model was greater than or equal to 30, the effect of particle size on the soil-bearing capacity could be ignored. When the ratio of the net distance from the foundation to the model boundary to the foundation width was greater than or equal to 2, the bearing capacity of the soil was not significantly affected by the model boundary, and the boundary effect could be ignored. With the increase in foundation width, the bearing capacity factor of the soil decreased, and the failure mode of the soil shifted from a general shear failure to a local shear failure or punching shear failure. This research in this paper not only offers valuable insights for downscaling numerical discrete element models, but also introduces novel approaches for macro-microscopic characterization of soil-bearing capacity.