Microscale Energy Dissipation Mechanisms in Cyclically-Loaded Granular Soils

Abstract

This paper utilizes the Discrete Element Method to characterize energy dissipation mechanisms in cyclically loaded soils based on micromechanical considerations. Computational simulations of consolidated undrained cyclic triaxial tests were conducted at various relative densities and were subjected to cyclic loading of different frequencies and shear strain amplitudes. The different components of microscale energies were monitored during the course of the simulations and characterized into input and dissipated energies. A comparison is made between the dissipated energy computed from microscopic energy components and macroscopic energy calculated based on the area of the deviator stress-axial strain loops. These energies are then used to obtain the specific damping capacity defined as the ratio of dissipated energy during one cycle to the maximum stored elastic energy during the same cycle. The conducted simulations highlight the importance of calculating actual stored energy in the system as opposed to approximating it to be that calculated as the triangular area under the secant modulus. Finally, a series of simulations that resulted in liquefaction are discussed, and the amount of energy dissipated to liquefaction is examined based on these results.

Energy dissipation in soil samples during drained triaxial shearing

“…A wide range of energy-based approaches have been proposed to predict the seismic liquefaction potential of a sand (e.g., Berrill & Davis, 1985;Law et al, 1990;Figueroa et al, 1994;Trifunac, 1995). The damping ratio, which quantifies the energy dissipated during cyclic loading, is often computed using the areas underneath and enclosed by a hysteresis loop on a stress-strain plot (e.g., experiments of Seed et al, 1986;Vucetic & Dobry, 1991; simulations of Sitharam & Vinod, 2010;El Shamy & Denissen, 2012). This method of computing energy terms is limited to distinguishing energy dissipated during the loading cycle and the maximum elastic energy stored during the cycle for the entire system.…”

A simple non-linear model for internal friction in modified concrete

“…On the other hand, the classical works [83,146] study the internal mechanisms of dissipation in solids when no relevant damage phenomena occur at the macroscopic level. In the same spirit are the papers [117,66,65,54,132,147] where several models for dissipation of energy due to elastic deformation rate and relative motion of different parts of considered bodies are studied and applied in the case of metals or even concrete. Finally, two papers which accept a point of view very similar to ours are [1,20] where the internal dissipation mechanism are clearly distinguished in two different types: one producing crack generation and growth, the second being related to reversible relative motion of micro-crack lips.…”

Effective additive for foam concrete

“…Currently, finely-ground limestone with a nanoscale component is used to modify and improve concrete properties [1]. This is due to the ability of fine-ground limestone to interact with concrete clinker components at the physical and partially chemical levels, forming a monolith [2,3]. The positive effect of carbonate fillers is explained by the fact that they have a chemical affinity with cement, which leads to the formation of a dense contact between them and the fusion of hydration products of cement with the filler during natural hardening.…”