Numerical analysis of the effect of the gradation characteristics of soil particles on the ground bearing capacity of a rigid footing via the discrete element method

Abstract

To underscore the overestimation of the ground bearing capacity by continuum-based numerical or analytical methods, the discrete element method (DEM), which may capture the microscopic characteristics of soil with graded particles, is used to study the ultimate bearing capacity of the ground (p_u). In this work, the rolling resistance linear model of contact is implemented by the DEM for the soil, so the ultimate bearing capacity of the ground can be predicted. During the loading process in the DEM test, the development of a failure zone (or shear band) in the ground can be observed. Numerical experiments reveal that there is a certain negative linear relationship between the footing’s ultimate rotation angle (α_u) and p_u, offering a novel perspective on the study of p_u. Due to the asymmetry of the DEM ground, a new modification factor η_p is defined for the ultimate bearing capacity. It is found that particularly for soils with a large mean particle size, narrow gradation or poor continuity of the particles, the effect of particle gradation characteristics on the ultimate bearing capacity should be appropriately evaluated.

Keywords

ultimate ground bearing capacity / soil with graded particles / discrete element method / uneven settlement / rotation of footing

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