Evaluating the hydromechanical responses of seabed-pipelines with rotated anisotropic heterogeneous seabed properties

摘要

Seabed sediments are inherently heterogeneous and present different fabric patterns including rotated anisotropy. This work aims to investigate the effects of rotated anisotropy in seabed properties on the hydromechanical responses of seabed and pipelines. Rotated anisotropic seabed property fields (e.g., hydraulic conductivity and shear modulus fields) are generated using the random field theory, and are then coupled with finite element models to simulate the hydromechanical responses of seabed-pipelines under dynamic nonlinear wave-induced loadings. Monte Carlo simulations are performed to approach a probabilistic analysis of the effects of heterogeneous seabed fields. The pore pressure, liquefaction, seabed displacement, and pipeline stress are analyzed for systematic varying rotation angles. The results show that the upper bounds of the liquefied area would decrease by about 15% and 8% with increasing rotated anisotropy in the hydraulic conductivity and shear modulus fields, respectively. For rotated anisotropic shear modulus fields, the von Mises stress is minimum when the rotation angle is 45 degrees. The transverse anisotropy in hydraulic conductivity or shear modulus is the most unfavorable situation, the results of which could be relied upon for a conservative design if the rotated anisotropy of a seabed property is unknown in a field project.