Relationship between acoustic emission and energy dissipation: a DEM study of soil-structure interaction

Acoustic emission (AE) monitoring offers the potential to sense particle-scale interactions that lead to macro-scale responses of granular materials; however, there remains a paucity of understanding of the fundamental links between particle-scale mechanisms and AE generation in particulate materials, which limits interpretation of the measured AE. The objective of this study was to establish links between particulate-scale energies and AE activity measured at the macro-scale in experiments. To achieve this, a programme of 3D DEM simulations was performed on granular soil/steel structure interfaces and the results were compared with experimental measurements. The findings show that the fundamental particulate-scale mechanisms that contribute to AE generation are friction and damping in particulate rearrangement, with friction being the dominant mechanism (i.e. >95% of the total energy). Dissipated plastic energy was influenced in the same way as measured AE activity by unload-reload behaviour, imposed stress level, mobilised shearing resistance, and shearing velocity. Relationships have been established between AE and dissipated plastic energy (R2 from 0.96 to 0.99), which show AE generated per Joule of dissipated plastic energy is significantly greater in shearing than compression. A general expression has been proposed that links AE and plastic energy dissipation. This new knowledge enables improved interpretation of AE measurements and underpins the development of theoretical and numerical approaches to model and predict AE behaviour in particulate materials.