Stiff Degradation of Granular Material – A DEM Approach
The stiffness degradation of granular materials such as soils due to cyclic loading has been widely explored in the experimental studies, mostly in triaxial or oedometer apparatus. Such behaviour can be observed due to the cyclic loading at very small strains, which is considered as elastic range. While increasing the cyclic strain amplitude, the stiffness or secant shear modulus (G) reduces non-linearly and forms a S-shaped curve with the shear strain (γ). A discrete element method (DEM) is adopted in this study to have enhance the understanding of soil response to cyclic strain amplitude. It was found later in this study that the stiffness of granular material reduced as void ratio (e) increased. The maximum stiffness was highly dependent on e, but not p′. However, the normalized stiffness degradation curve was influenced by both initial states i.e. e and p′; p′ seemingly had more impact of the normalized stiffness degradation than e.
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