The transition into a glassy state of a tapped granular pile is explored in
detail using extensive molecular dynamics simulations. We measure the density
and density fluctuations of the ensemble of mechanically stable configurations
reached after the energy induced by the perturbation has dissipated. We show
that the peak in density fluctuations concurs with the density undergoing the
transition. We find that different horizontal sub-regions ("layers") along the
height of the pile traverse the transition in a similar manner but at distinct
tap intensities, demonstrating that at a given intensity certain regions of the
same pile may respond glassy while others remain equilibrated. To address this
phenomenon, we supplement the conventional approach based purely on properties
of the static configurations with investigations of the grain-scale dynamics,
induced by a tap, by which the energy is transmitted throughout the pile. We
find that the effective energy that particles dissipate is a function of the
particles location in the pile and, moreover, that its value plays a
distinctive role in the transformation between configurations. This internal
energy provides a "temperature-like" parameter that allows us to align the
transition into the glassy state for all layers as well as different annealing
schedules at a critical value.