An experimental study of shock-induced wave propagation in dry, water-saturated, and partially saturated porous media

Wave propagation in a porous column consisting of fixed sand particles, is studied by subjecting the pore fluid to a step-wise pressure increase in a shock tube. Pore pressures and strains of the porous column are measured at different locations. With air as a pore fluid the pore pressure is fully determined by linear and non-linear interaction forces. For the water-saturated case the expected two-wave structure is observed and is reasonably well described by linear two-phase theory if the frequency dependence of the interaction is taken into account. Wave propagation in and reflection from a porous column is strongly affected by a small volume fraction of air bubbles in the pores.