Drainage effects on suction force beneath offshore perforated mudmats

For offshore perforated mudmats installed on low-permeability clay, the underneath suction force is an important component of the uplift resistance during removal and can be effectively reduced by perforation. Since the perforation may result in partial drainage of the soil, the effect of the uplift rate on the drainage condition and suction force is analysed in this study using the small strain finite element with the modified Cam Clay (MCC) model. Considering that water can stably accumulate beneath the mudmat, soft porous elastic water elements are used to simulate the interface and the compression is blocked by the proposed equivalent thickness element. The trend of increasing and then decreasing suction force with reducing normalized extraction rate V is studied, curve fitting is provided, and the mechanism is interpreted from both element-scale and macro-scale perspectives. The effects of soil strength heterogeneity, preload, and perforation width on suction force with drainage conditions are also discussed.

Automated summary

This study investigates the effect of uplift rate on drainage conditions and suction force, and finds that the suction force increases and then decreases with reducing extraction rate. The study also discusses the effects of soil strength heterogeneity, preload, and perforation width on suction force with drainage conditions.