Advancing Understanding of the Influence of Drained Cyclic Loading on Sand Behavior Using DEM

Understanding the response of sand to drained cyclic loading is relevant to the design of abutments of integral bridges and foundations of wind turbines among other applications. In this study, the discrete element method (DEM) was applied to simulate drained triaxial element tests. The simulations were able to reproduce trends observed in physical laboratory experiments. The loading amplitude determined the observed material behavior during cyclic loading. Specifically, similar behavior was observed at different mean effective stresses when applying the same ratio of loading amplitude to mean effective stress. A key question is how the application of drained low-amplitude load cycles can influence the mechanical response of the material. A number of monotonic drained and undrained shearing tests were carried out on digital snapshots that recorded the sample state at various instances during cyclic loading. While there was systematic variation in the response as a function of the number of load cycles with monotonic undrained shearing, the responses in drained shearing were less sensitive to the number of load cycles applied. Clear correlations between the maximum deviatoric stress, the void ratio, mechanical coordination number, and degree of anisotropy were confirmed by the DEM simulations. These links were previously hypothesized in laboratory experiments.