Experiments on the Sinking of Marine Pipelines on Clayey Soils

An experimental study was carried out to investigate seabed-pipeline interactions with regard to soil liquefaction. For a soil with a high proportion (30 to 60%) of fine sediment, four groups of tests were configured to reproduce soil liquefaction around pipelines for different initial pipe depths, pipe densities and wave conditions (wave height and period). The study focused on verifying the theoretically computed areas of soil failure by analyzing the sinking depths of the pipelines. The main findings are that a pipe with a submerged specific weight of less than half that of the soil will move up to the mudline; that the loss of soil loading capacity is more frequently evidenced in a fluid-like behavior of the soil than by an abrupt breaking of the soil matrix; and that the pipes which are totally buried will sink more than half-buried pipes. Moreover, wave action and the specific weight of the pipes seem to play more important roles in the expected behavior of the wave-soil-pipe interaction than the initial water content of the mud.