Abstract
This study presents results from field data observed from Hangzhou Bay Subsea Pipeline (HBSP) to investigate the burial characteristics of subsea pipelines with spoiler on silty seabed. The study is based on large-scale seabed topography data and continuous ten years of pipeline route survey data conducted between 2005 and 2014. Analysis of surveyed data shows that along the pipeline route, seabed evolution around HBSP has three zones: continuous scour, scour followed by deposition, and continuous deposition zone. For continuous scour, pipeline remains exposed, and pipeline with spoiler induced full self-burial doesn't take effect. While for continuous deposition and scour followed by deposition, the combined effects of self-burial and seabed evolution increase average total burial depth from 1.5m in 2006 to 3.5m in 2014. Spoiler attached to pipeline is the main factor to increase total burial depth before 2006, and by 2014, the contribution of seabed deposition to burial depths far exceeds that of self-burial. The self-burial depth is over 2.0D (D is pipeline diameter) under bidirectional tidal flow while it is no more than 1.0D under unidirectional flow. These findings provide technical support for the implementation of spoiler in offshore pipelines under similar hydrodynamic and sediment conditions.
Published Version
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