Acoustic wave propagation in granular media

Abstract

The frame bulk and shear moduli are important in analyzing the acoustic wave propagation in marine sediments. The frame bulk and shear moduli of marine sediment are related to the longitudinal and shear wave velocities in dry marine sediments. The measured results of the longitudinal wave velocities in dry glass beads with four different grain sizes, but with almost the same porosity have been reported. The measured results showed that the longitudinal wave velocity largely increases, as the grain size increases. This result could not be explained using the classical contact theory, such as the Hertz–Mindlin or Digby model. In this study, we use the longitudinal wave velocities of dry glass beads in air and in vacuum to investigate the effects of the air, as the pore fluid. The measured results show that the longitudinal wave velocities in vacuum are smaller than that in air, and the velocities in vacuum become almost constant, even though the grain sizes are different.