  Confinement of a slender body into a granular array induces stress
localization in the geometrically nonlinear structure, and jamming, reordering,
and vertical dislocation of the surrounding granular medium. By varying the
initial packing density of grains and the length of a confined elastica, we
identify the critical length necessary to induce jamming, and demonstrate an
intricate coupling between folds that localize along grain boundaries. Above
the jamming threshold, the characteristic length of elastica deformation is
shown to scale with the length over which force field fluctuations propagate in
a jammed state, suggesting the ordering of the granular array governs the
deformation of the slender structure. However, over confinement of the elastica
will induce a form of stress relaxation in the granular medium by dislocating
grains through two distinct mechanisms that depend on the geometry of the
confined structure.
