非线性海床土深水缓波型立管动力响应分析

Dynamic response analysis of deepwater laze-wave SCR based on a nonlinear seabed soil model

缓波立管的结构形式能够有效改善立管触地区的动力响应,达到保护立管触地区的目的。基于集中质量法和考虑土体弱化的非线性海床土模型,用等效浮力的方法将缓波立管浮力段简化,并在Orca Flex中建立传统钢悬链线立管和缓波立管的集中质量模型进行分析,考虑立管结构形式、浮力段长度和浮力段起始位置的影响,得到立管静态位形、触地点张力和弯矩、立管贯入深度以及触地点海床阻力等结果进行比较。结果表明:浮力段的配置会提高立管静态弯矩分布水平,但合理的缓波立管设计能有效改善立管触地区的动力响应,抑制海底沟槽的发展,达到保护立管触地区的目的。

The structure of lazy-wave SCR can effectively improve the dynamic response of the riser and achieve the purpose of protecting the riser’s touchdown area.In this work,the lumped-mass models of traditional SCR and lazy-wave SCR were established in OrcaFlex based on the lumped-mass method and the nonlinear seabed soil model considering the weakening of soil.And the equivalent buoyancy method was adopted to simplify the buoyancy section of the lazy-wave SCR.Considering the influence of the structure of risers,the length of the buoyancy section and the starting position of the buoyancy section,a comparison between traditional SCR and lazy-wave SCR was carried out in terms of static configuration of risers,effective tension and bending moment of the touchdown point,penetration depth of risers and resistance of the seabed at the touchdown point.The results indicate that the configuration of the buoyancy section will increase the distribution level of the static bending moment of the riser.However,the reasonable design of the lazy-wave SCR can effectively improve the dynamic response of the riser in the touchdown area,restrain the development of the subsea trench and achieve the purpose of protecting the riser’s touchdown area.