Synchronized oscillations and acoustic fluidization in confined granular materials
de Arcangelis, L.
Pica Ciamarra, Massimo
Date of Issue2018
School of Physical and Mathematical Sciences
According to the acoustic fluidization hypothesis, elastic waves at a characteristic frequency form inside seismic faults even in the absence of an external perturbation. These waves are able to generate a normal stress which contrasts the confining pressure and promotes failure. Here, we study the mechanisms responsible for this wave activation via numerical simulations of a granular fault model. We observe the particles belonging to the percolating backbone, which sustains the stress, to perform synchronized oscillations over ellipticlike trajectories in the fault plane. These oscillations occur at the characteristic frequency of acoustic fluidization. As the applied shear stress increases, these oscillations become perpendicular to the fault plane just before the system fails, opposing the confining pressure, consistently with the acoustic fluidization scenario. The same change of orientation can be induced by external perturbations at the acoustic fluidization frequency.
Physical Review E
© 2018 American Physical Society (APS). This paper was published in Physical Review E and is made available as an electronic reprint (preprint) with permission of American Physical Society (APS). The published version is available at: [http://dx.doi.org/10.1103/PhysRevE.97.010901]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.