Water wave-driven seepage in marine sediments

The action of water waves moving over a porous seabed drives a seepage flux into and out of the marine sediments. The volume of fluid exchange per wav e cycle may affect the rate of contaminant transport in the sediments. In t his paper, the dynamic response of the seabed to ocean waves is treated ana lytically on the basis of pore-elastic theory applied to a porous seabed. T he seabed is modelled as a semi-infinite, isotropic, homogeneous material. Most previous investigations on the wave-seabed interaction problem have as sumed quasi-static conditions within the seabed, although dynamic behaviour often occurs in natural environments. Furthermore, wave pressures used in the previous approaches were obtained from conventional ocean wave theories : which are based on the assumption of an impermeable rigid seabed. By intr oducing a complex wave number, we derive a new wave dispersion equation, wh ich includes the seabed characteristics (such as soil permeability, shear m odulus, etc.). Based on the new closed-form analytical solution, the relati ve differences of the wave-induced seabed response under dynamic and quasi- static conditions are examined. The effects of wave and soil parameters on the seepage flux per wave cycle are also discussed in detail. (C) 2000 Else vier Science Ltd. All rights reserved.