Transient Responses of Porous Media under Moving Source Excitations

Abstract

Three-dimensional transient responses of porous media under moving source excitations with finite frequency components are theoretically studied. We discuss three free-surface drainage conditions: permeable—“open pore”, impermeable—“closed pore”, and partially permeable boundaries that are firstly considered. The transient responses of vertical displacements and pore fluid pressures triggered by the sources moving on the surface are investigated. Typical surface drainages, moving velocities, material permeabilities and source wavelets are discussed in detail. It is concluded that the R1 surface wave carries the strongest energy as that for stationary source configurations. Moreover, it has higher sensitivity to surface drainage condition than body waves in the responses of peak amplitudes and locations of the wave forms. The apparent moving velocities of the exciting source toward the receiver may cause ‘blue shift’ in frequency responses, that is, the higher moving velocity triggers more obvious dominating frequency shift.