Discrete element method simulation of dynamic deformation characteristics of lightweight soil with different EPS particle volume ratios

Аннотация

 In this study, to explore laws governing the influence of the expanded polystyrene (EPS) particle volume ratio on the dynamic deformation characteristics of lightweight soil, indoor dynamic triaxial tests and a discrete element numerical simulation of lightweight soil with EPS particle volume ratios of 40%, 50%, and 60% were carried out under the condition of a cement mixing ratio of 15%. Consequently, macro hysteresis curves and the distributions of micro contact force, velocity field, and displacement field were obtained. The results revealed that considering the dynamic strength of lightweight soil with a cement content of 15% and an EPS particle volume ratio of 40% as the standard, the dynamic strength of lightweight soil decreased by 22.75%–28.23% and 35.58%–42.02% with an increase in the EPS particle volume ratio to 50% and 60%, respectively. During the loading process, the contact force, velocity, and displacement of particles increased continuously and reached their maximum values at the time corresponding to the vertex of the hysteresis loop. During the unloading process, the contact force between the particles decreased, the velocity direction changed, and the displacement decreased gradually. However, unloading simply reduced the displacement, while the displacement direction of the particles still pointed from the two ends of the sample towards the middle of the sample, which resulted in a macro compressed deformation of the sample. With an increase in the EPS particle volume ratio, the volume of the soil particle skeleton decreased. In addition, a small amount of soil particles surrounding the EPS particles attained extremely high velocities, resulting in a decrease in the bearing capacity of the sample, thereby rendering the sample more prone to damage. This observation is consistent with the law that the dynamic strength of the sample decreases with an increase in the EPS particle volume ratio.