Investigation on scour scale of piggyback pipeline under wave conditions. (15th June 2019)

• Record Type: Journal Article
• Authors: Yang, Shaopeng; Shi, Bing; Guo, Yakun
• Is Part Of: Ocean engineering. Volume 182(2019)
• Page Start: 196
• Page End: 202
• Publication Date: 2019-06-15
• Subjects: Piggyback pipeline -- Scour depth -- Scour width -- Gap-ratio -- Spacing -- Wave action; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2019.04.074
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Laboratory experiments are presented to investigate the effect of different piggyback pipeline configurations on the morphology of local scour under wave conditions. Scour depth and width around the pipelines under regular and irregular waves are measured and analyzed for a range of pipeline and wave conditions; such as the spacing between two pipes ( G ), gap between the main pipe and seabed ( e ), pipe diameter ( D ), wave height ( H ) and period ( T ). Experimental results reveal that both the scour depth and width around piggyback pipeline is much larger than those around single pipe under the same wave conditions. Scour depth increases with the increase of the Keulegan-Carpenter ( KC ) number and decreases with increase of G and e . When e exceeds 0.5D, scour depth tends to approach 0. When spacing G is greater than 0.4D, the destabilization from small pipe to large one is greatly reduced, resulting in scour depth around piggyback pipeline being close to that around single pipe. Similar to scour depth, scour width broadens with the increase of KC number increasing and decreases with the increase of G . Experiments also show that the effect of e on scour depth is greater than that of G under the same test conditions, while their impact on scour width is opposite. Furthermore, scour width under irregular waves is extended slightly compared with regular wave for otherwise the identical conditions. Highlights: The maximum scour depth and width around piggyback pipelines is much larger than main pipe with same wave conditions. The effect of gap e on the scour depth is greater than that of spacing G, while the scour width is in the opposite. The scour width under irregular waves is slightly larger than that with the regular wave action.