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Effect of Shear Stiffness Degradation on Accumulation of Pore Water Pressure in Marine Sediments
Haonan Cui and Xiaoli Liu

Liquefaction of marine sediments caused by wave-induced accumulation of pore water pressure may lead to damage of submarine pipelines, resulting in oil spills and pollution of the marine environment. Meanwhile, accumulated pressure may change the flow path of pore water, which has an influence on transport of solutes in sediments. Most of the previous investigations on wave-induced pore pressure accumulation in marine sediments have neglected the degradation of soil shear stiffness caused by the corresponding excess pore pressure. In this study, the effect of degradation of soil shear stiffness on pore pressure accumulation is investigated by numerical simulation. Reliability of the numerical modeling framework has been verified by comparison with the results of flume and centrifuge tests. The numerical simulation results have shown that the shear stiffness degradation of sediments accelerates build-up of pore water pressure and leads to its sudden increase on liquefaction at shallow soil depth. The degree of shear stiffness degradation induced by accumulated excess pore pressure varies with depth, resulting in non-uniform distribution of shear modulus in the vertical direction, which leads to an increase of sediment shear stress and further advances the build-up of pore water pressure.

Keywords: Wave, marine sediments, accumulation of pore water pressure, shear stiffness degradation, seabed response, liquefaction

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