  Jammed states of frictional granular systems can be induced by shear strain
at densities below the isostatic jamming density ($\phi_c$). It remains
unclear, however, how much friction affects this so-called shear-jamming.
Friction appears in two ways in this type of experiment: friction between
particles, and friction between particles and the base on which they rest.
Here, we study how particle-bottom friction, or basal friction, affects shear
jamming in quasi-two dimensional experiments. In order to study this issue
experimentally, we apply simple shear to a disordered packing of photoelastic
disks. We can tune the basal friction of the particles by immersing the
particles in a density matched liquid, thus removing the normal force, hence
the friction, between the particles and base. We record the overall shear
stress, and particle motion, and the photoelastic response of the particles. We
compare the shear response of dry and immersed samples, which enables us to
determine how basal friction affects shear jamming. Our findings indicate that
changing the basal friction shifts the point of shear jamming, but it does not
change the basic phenomenon of shear jamming.
