"Quaking" in flows of tightly packed granular particles (2): Facts from laboratory observations with 3D internal imaging."

In timescales shorter than a second, tightly-packed grains under applied shear exhibits intermittent rearrangements across a wide range of spatial scales. We introduce a new geometry named Circular Shearing as an extension to our previous work [Phys. Rev. Lett. 126.128001 (2021)] and focus on the particle-level behaviors associated with the intermittent events, or "quaking" for short. Fast, three-dimensional scanning of the internal bulk under continuous shearing allows us to reconstruct the microstructure and to observe its evolution approaching or following the apparent "discontinuities" over the quaking. Our preliminary results encompass analyses on displacement jumps, the distributed local shear strain, non-affine residues, and spatiotemporal correlations of these quantities, revealing the nature of the quaking intermittency.