Numerical simulation of pore pressure development beneath suction anchor under undrained condition during uplift

Suction anchors are increasingly used in the deep-sea anchoring infrastructure, and the accurate evaluation of the uplift behavior is of great importance. In this paper, the development of pore pressure under the suction anchor lid during the undrained pullout process was investigated. The numerical model based on the solid-fluid two-phase theory and by updated Lagrangian method was employed. Laboratory experimental studies with three different aspect ratios were carried out to verify the effectiveness and accuracy of numerical method. Parametric studies were performed to analyze the effect of key soil properties on the accumulation of pore pressure. The results show that the numerical method in terms of capturing the failure pattern and simulating pore pressure evolution was significantly efficient. The development of excess pore pressure increased faster at the beginning, followed by a slower increase and then tended to level off. The maximum excess pore pressure appeared just beneath the suction anchor, and decreased with the increasing soil depth. Parametric analysis showed that a greater negative pore pressure needed a larger shear modulus, MCC swelling index and critical stress ratio, or a smaller porosity, permeability and MCC compression index. The softening coefficient had little effect on the pore pressure generation.