Experimental and numerical investigation on hydrodynamic behavior of a long curved pipeline system with multiple floating bodies in immersion construction

In practice, underwater pipeline needs to be designed into an irregular shape with multiple floating bodies due to special design and construction requirements. The pipeline alignment further increases the difficulty and risk of its immersion construction. With an aim to reduce the potential risk and cost, an in-depth experimental and numerical investigation is carried out using a large-scale wave-current flume and the OrcaFlex software, respectively, for examining the hydrodynamic behavior of a long curved river crossing pipeline system with multiple floating bodies. The results from numerical simulation, site construction, and model experiment are compared to assess the effectiveness of modeling, with an error of less than 5% between different approaches. Sensitivity analyses are conducted to understand the effect of deflate ways of gasbags, flow speed and coordination of hanger ropes. Results show that the irregular structure shape of the pipeline can induce the taut-slack phenomenon of hanger ropes. If the consistency in control of hanger ropes cannot be ensured, large tension could occur in different ropes. The present study provides important theoretical and technical guidance for construction of large-scale immersion systems of irregular shaped pipeline with multiple floating bodies.