考虑非线性管-土接触模型的钢悬链线立管触地区动态曲率分析
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摘要
钢悬链线立管(SCR)具有特殊的结构型式,循环载荷作用下,由于海床模型的不确定性易导致触地区产生较高的弯曲应力,引发疲劳损伤。基于非线性P-y曲线管-土接触模型,运用大挠度曲线梁模型来模拟SCR与海床土的相互作用,研究SCR在浮体二维运动和海床作用下,触地区的动态曲率变化情况。由计算结果可知:1)由于在立管的有效张力中考虑局部曲率的影响,导致立管触地区的有效张力显著增加,并产生较高的弯矩; 2)动态分析中,分别运用线弹性海床和非线性海床模型,研究立管触地区的相对曲率随相对时间的变化曲线,表明非线性海床将使触地区的相对曲率具有明显的非线性,且有多个峰值,变化幅度较大,并出现反向曲率; 3)垂荡运动比纵荡对曲率的影响大,且运动幅值越大,影响越明显。
The TDP of SCR,having especial structural form,attracts the worst bending stresses due to the cyclic loads and is subject to the greatest uncertainties,such as those arising from the riser-seabed contact. SCR-soil interaction is simulated by the nonlinear Py curve and SCR is simulated by flexible curve beam with large curvature. The dynamic curvature at TDP is studied when an oscillatory motion and pipe-soil interaction are applied to the riser. The results are shown in figures and indicate that: 1) Due to the influence of local curvature in the effective tension,effective tension at TDZ of riser is significantly increased and the bending moment is the highest in static analysis; 2) In the dynamic analysis,the variation trends of relative curvature at TDZ with relative time are presented considering the linear elastic and nonlinear seabed model. The comparative analysis by useing a nonlinear seabed model shows that the curves have obvious nonlinearity and multiple peaks,and the variation amplitude of curvature is very large and there are reverse curvatures; 3) The effect of heave motion on curvature is greater than that of surge oscillation,and the effect is more obvious with the increase of motion amplitude.
The TDP of SCR,having especial structural form,attracts the worst bending stresses due to the cyclic loads and is subject to the greatest uncertainties,such as those arising from the riser-seabed contact. SCR-soil interaction is simulated by the nonlinear Py curve and SCR is simulated by flexible curve beam with large curvature. The dynamic curvature at TDP is studied when an oscillatory motion and pipe-soil interaction are applied to the riser. The results are shown in figures and indicate that: 1) Due to the influence of local curvature in the effective tension,effective tension at TDZ of riser is significantly increased and the bending moment is the highest in static analysis; 2) In the dynamic analysis,the variation trends of relative curvature at TDZ with relative time are presented considering the linear elastic and nonlinear seabed model. The comparative analysis by useing a nonlinear seabed model shows that the curves have obvious nonlinearity and multiple peaks,and the variation amplitude of curvature is very large and there are reverse curvatures; 3) The effect of heave motion on curvature is greater than that of surge oscillation,and the effect is more obvious with the increase of motion amplitude.
引文
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[13]ARANHA J A P,MARTINS C A.The soil rigidity effect in the touchdown boundary-layer of a catenary riser:static problem[C]//Proceedings of the International Offshore and Polar Engineering Conference.1998.
[14]ARANHA J A P,MARTINS C A,PESCE C P.Dynamic curvature in catenary riser at the touchdown point region:an experimental study and the analytical boundary-layer solution[J].International Journal of Offshore and Polar Engineering,1998,8(4):303-310.
[15]BRIDGE C,LAVER K,CLUKEY E,et al.Steel catenary riser touchdown point vertical interaction models[C]//Proceeding of Offshore Technology Conference,OTC16628.2004:1-9.
[2]ARANHA J A P,MARTINS C A,PESCE C P.Analytical approximation for the dynamic bending moment at the touchdown point of a catenary riser[C]//Proceedings of the International Offshore and Polar Engineering Conference.1997,7(4):293-300.
[3]LUCIANO A C,MARTINS C A.Nonlinear dynamic response of a steel catenary riser at the touchdown point[C]//Proceedings of the International Offshore and Polar Engineering Conference.2001:234-238.
[4]QUEAU L M,KIMIAEI M,RANDOLPH M F.Dimensionless groups governing response of steel catenary risers[J].Ocean Engineering,2013,74(12):247-259.
[5]QUEAU L M,KIMIAEI M,RANDOLPH M F.Analytical estimation of static stress range in oscillating steel catenary risers at touchdown areas and its application with dynamic amplification factors[J].Ocean Engineering,2014,88(9):63-80.
[6]QUEAU L M,KIMIAEI M,RANDOLPH M F.Sensitivity studies of SCR fatigue damage in the touchdown zone using an efficient simplified framework for stress range evaluation[J].Ocean Engineering,2015,96(3):295-311.
[7]常爽,黄维平,杨超凡.非线性海床土对钢悬链式立管触地点动力响应和疲劳损伤影响分析[J].海洋工程,2017,35(2):67-74.(CHANG Shuang,HUANG Weiping,YANG Chaofan.The influence of nonlinear seabed on the dynamic response and fatigue damage of SCR at TDZ[J].The Ocean Engineering,2017,35(2):67-74.(in Chinese))
[8]梁宁,黄维平,杨超凡.钢悬链式立管与非线性海床土相互作用分析方法研究[J].海洋工程,2016,34(1):40-49.(LIANG Ning,HUANG Weiping,YANG Chaofan.Study on method of interaction between steel catenary riser and nonlinear seabed[J].The Ocean Engineering,2016,34(1):40-49.(in Chinese))
[9]白兴兰,黄维平,谢永和,等.非线性管-土作用下钢悬链线立管触地区疲劳分析[J].工程力学,2016,33(3):248-256.(BAI Xinglan,HUANG Weiping,XIE Yonghe,et al.Fatigue analysis of steel catenary riser at touchdown zone under nonlinear riser-soil interaction[J].Engineering Mechanics,2016,33(3):248-256.(in Chinese))
[10]RANDOLPH M,QUIGGIN P.Non-linear hysteretic seabed model for catenary pipeline contact[C]//Proceedings of the 28th International Conference on Offshore Mechanics and Arctic Engineering.2009:145-154.
[11]AUBENY C P,BISCONTIN G.Seafloor-riser interaction model[J].International Journal of Geomechanics,2009,9(3):133-141.
[12]BAI Xinglan,HUANG Weiping,MULIRO A V,et al.Riser-soil interaction model effects on the dynamic behavior of a steel catenary riser[J].Marine Structures,2015,41(4):53-76.
[13]ARANHA J A P,MARTINS C A.The soil rigidity effect in the touchdown boundary-layer of a catenary riser:static problem[C]//Proceedings of the International Offshore and Polar Engineering Conference.1998.
[14]ARANHA J A P,MARTINS C A,PESCE C P.Dynamic curvature in catenary riser at the touchdown point region:an experimental study and the analytical boundary-layer solution[J].International Journal of Offshore and Polar Engineering,1998,8(4):303-310.
[15]BRIDGE C,LAVER K,CLUKEY E,et al.Steel catenary riser touchdown point vertical interaction models[C]//Proceeding of Offshore Technology Conference,OTC16628.2004:1-9.