Numerical Analysis of Liquefaction of Porous Seabed around Submarine Pipeline under Seismic Loading

The liquefaction of seabed under seismic loading is one of the main reasons that govern the overall stability of submarine pipeline.In this paper, a FEM numerical analysis method on liquefaction around a buried pipeline in sandy seabed under seismic loading is presented.The advanced soil static and dynamic universal triaxial and torsional shear apparatus is employed to perform cyclic torsional shear tests subjected to cyclic loading, and the mode of dynamic increase of pore pressure under undrained conditions gained from tests is incorporated with two-dimensional dynamic consolidation equation and a numerical procedure based on FEM is developed to assess the accumulative pore pressure.By numerical computations, the accumulation process of pore pressure and liquefaction potential of seabed soil during seismic loading can be evaluated.Based on the numerical model presented in this paper, the effects of soil characteristic parameters and pipeline geometry on the seismic-induced accumulative pore pressure around submarine pipeline and along the depth of seabed are studied in detail.