Subsea Pipeline Stability in Various Trench Sections

초록

For pipelines in trench the velocity and acceleration of water particle are dramatically reduced which affect on the stability. To predict the stability of pipeline in trench, the reduction factors are often used. However, the known reduction factors are limited to specific conditions with defined slopes and trenched depths. To verify the stability in various trench, the experiment was conducted with the advanced PIV technology. The circular cylinder model for pipeline is fixed in trench section at various trench depths and slopes. Four different velocities of current are generated at the circulating water channel. The velocities around the cylinder are measured and recorded. Even the current is at constant velocity, there are cyclic circular motions created around the cylinder. The horizontal and vertical velocities in front and back of the cylinder are investigated at each current condition. The results show that the trench depth and slope influence greatly on pipeline stability.