钢悬链式立管管土耦合作用的吸力效应研究

钢悬链式立管（steel catenary riser，简称SCR）的流线段敷设在海床上，在浮体运动和环境荷载作用下管线作拔出海床的上升运动时，软质海床的黏性性质将阻碍管线的拔出而表现出吸力效应。吸力的大小与管线的拔出速度和管土循环作用次数、土的重塑时间等相关。基于现有试验数据拟合得到吸力数值模型，用于改进立管动力分析程序，研究立管拔出速度和管径等对触地区吸力分布、动态响应和疲劳寿命的影响。结果表明：海床土吸力对立管触地区应力特别是弯曲应力的影响较大，二者的变化趋势相似；管径的影响主要体现在贯入深度与管径的相对大小，同一贯入速度下，管径越小则相对贯入深度越大，拔出位移与吸力也会越大，反之则越小；立管的拔出速度是影响海床吸力最大值和拔出位移的主要因素，土吸力和拔出位移随拔出速度的增大而增大，导致触地区的疲劳损伤加剧。因此，探究管土耦合作用的吸力效应及其对SCR触地区疲劳损伤的影响，可为SCR与复杂海床相互作用及工程应用提供重要参考。

Study on suction effect of pipe-soil coupling in steel catenary riser

The steel catenary riser (SCR) is laid on the seabed, and under the action of floating body motion and environmental loads, the pipeline exhibits an upward movement to pull out of the seabed. However, the viscous properties of soft seabed hinder the pipeline''s extraction, resulting in a suction effect. The magnitude of suction is related to the extraction speed of the pipeline, the number of pipe-soil interaction cycles, soil remolding time, and other factors. Based on existing experimental data, a numerical model for suction is developed to improve dynamic analysis programs for risers. The effects of extraction speed and pipe diameter on suction distribution, dynamic response, and fatigue life in the touchdown zone (TDZ) are investigated. Results show that seabed soil suction significantly affects stress in the TDZ, especially bending stress, with similar trends. The influence of pipe diameter is mainly reflected in penetration depth relative to diameter; smaller diameters result in greater relative penetration depth and extraction displacement, while larger diameters lead to the opposite. Extraction speed is a primary factor affecting maximum seabed suction and extraction displacement; both increase with extraction speed, exacerbating fatigue damage in the TDZ. Exploring the suction effect of pipe-soil coupling and its impact on fatigue damage in the TDZ can provide crucial insights for SCR interaction with complex seabeds and engineering applications.