On-bottom stability of a radial fin integrated surface-laid pipe-section against vertical penetration

Abstract

This study focuses on the on-bottom stability of surface-laid submarine pipelines during vertical penetration under thermal-induced buckling. Submarine pipelines are susceptible to buckling due to their high slenderness ratio, and the resistance to such displacement relies on pipeline stiffness and soil resistance. To investigate this, laboratory model tests were conducted using a scaled-down pipe section placed on a clay bed. The clay bed was prepared with remoulded Kaolin clay, ensuring uniform moisture content, and the model pipe was scaled down from a typical industry prototype. These tests were conducted in 2D plane strain conditions within a tank, equipped with observation windows to monitor pipe movement and soil behaviour. A significant improvement in the pipe section's penetration resistance and on-bottom stability was observed after incorporating fin in the pipe. The addition of fins altered the earth pressure distribution beneath the vertically loaded pipe, leading to a larger failure mechanism in the adjacent soil. Furthermore, the soil-surface-heaving progressed towards the tank wall with increasing angular distance between the radial fins. Thus, the research demonstrated the effectiveness of radial fins in enhancing the stability and resistance of submarine pipelines against vertical penetration, shedding light on potential improvements in submarine pipeline design and deployment.