From the stress response function (back) to the sandpile `dip'

TL;DR

This paper links the pressure dip at the bottom of a sandpile to the stress response in sheared granular layers, showing anisotropic elasticity explains the dip and suggesting a new way to probe granular texture.

Contribution

It demonstrates that the sandpile dip can be understood through anisotropic elastic response, connecting pile texture to shear-induced anisotropy using response function analysis.

Findings

Anisotropic elastic analysis qualitatively reproduces the sandpile dip.

Shearing induces texture anisotropy similar to that from avalanches.

Response functions can probe static granular packing texture.

Abstract

We relate the pressure `dip' observed at the bottom of a sandpile prepared by successive avalanches to the stress profile obtained on sheared granular layers in response to a localized vertical overload. We show that, within a simple anisotropic elastic analysis, the skewness and the tilt of the response profile caused by shearing provide a qualitative agreement with the sandpile dip effect. We conclude that the texture anisotropy produced by the avalanches is in essence similar to that induced by a simple shearing -- albeit tilted by the angle of repose of the pile. This work also shows that this response function technique could be very well adapted to probe the texture of static granular packing.