Seepage force on a pipeline buried in a poroelastic seabed under wave loadings

The water wave induced seepage force on a pipeline buried in the seabed is investigated. The seabedis modeled as a porous and elastic medium containing a nearly saturated pore water, which is generally known as the Biot model. The pipeline is assumed to be rigid. It is not supported by any anchoring force. The governing equations describing soil stresses as well as pore water pressure under periodic wave loadings are solved numerically using a Boundary Integral Equation Method. Numerical results of pore water pressure amplitude around the pipeline are compared with laboratory data. Agreement is fairly good. Sensitivities of pore water pressure response to different soil and fluid parameter are also examined. It is found that with realistic parameters the uplift seepage force on the pipeline can be as much as 60% of the displaced water weight if the pipeline is located in the pore water pressure boundary layer.