This paper quantitatively studies the transient dynamic response of a semi-submersible production platform with the loss of one or several positioning mooring lines.A semi-submersible platform,production risers,and po...This paper quantitatively studies the transient dynamic response of a semi-submersible production platform with the loss of one or several positioning mooring lines.A semi-submersible platform,production risers,and positioning mooring lines are all included in the numerical simulation.Increased motion of the semi-submersible platform,tension variation of the remaining mooring lines/risers and the risk of mooring line or riser clashing are all investigated through fully coupled time-domain analysis.Combined environmental loads are selected from irregular waves and the steady current varying from very rough to extreme sea conditions.Three dimension radiation/diffraction theories and Morison’s equation are applied to calculate first-order wave force and second-order mean drift force of floating semi-submersible platform.Nonlinear time-domain finite element methods are employed to analyze the behavior of mooring lines and risers.Results show that the failure of mooring lines seriously reduce the platform’s stability performance.The tension of the rest lines is also increased accordingly.Remaining lines which are closer to the failed lines will have larger tension increase to compensate.Line-Line distance provides practical information for the risk of clashing investigation.展开更多
This paper focuses on the research of a semi-submersible platform equipped with a DP-assisted mooring system. Based on the working principles of the DP-assisted mooring system and the model of the platform motion, a t...This paper focuses on the research of a semi-submersible platform equipped with a DP-assisted mooring system. Based on the working principles of the DP-assisted mooring system and the model of the platform motion, a time domain simulation program is applied to analyze the impact, in the case of one line failure, on the platform motion, power consumption of the thrusters and the tension of the mooring lines. The results show that, under the 10-year wind dominant, a one line failure will have little impact on the tension of the mooring lines. When the failure line is windward, the power consumption will increase greatly with a weakened position of accuracy. However when the failure line is leeward, the power consumption will be reduced with a partly strengthened oosition of accuracy.展开更多
Submerged floating tunnels(SFTs)are novel structures for transportation across long-and deep-strait regions.Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion,the...Submerged floating tunnels(SFTs)are novel structures for transportation across long-and deep-strait regions.Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion,the risk of local anchor cable failure is high,which can result in the progressive failure of the entire structure.In this study,experimental and numerical investigations are conducted to analyze the dynamic behavior of an SFT with different mooring styles under local cable failure.A custom-designed cable failure device and the birth-and-death element method are used to simulate cable failure(i.e.,progressive failure)via experiments and numerical simulation,respectively.A physical-scale segmental model of an SFT with different mooring styles under anchor cable failure is developed in this study.A segmental and entire-length mathematical model is developed using the ANSYS program to perform the numerical simulation.The results of the segmental numerical and experimental models indicate good agreement.The dynamic response of an SFT with different mooring styles under cable failure is comprehensively investigated by investigating the effects of key parameters(wave period,buoyant weight ratio,and cable failure mechanism).Moreover,the progressive failure of the SFT under cable failure is investigated via a segment model test and a numerical simulation of its entire length.The present study can serve as a reference for the safer designs of the SFT mooring style.展开更多
由于地震、断层、滑坡和沉降等原因,张力腿平台(tension leg platform, TLP)下端的桩基可能发生错动。考虑平台本体有限位移、六自由度运动耦合、瞬时位置和瞬时湿表面、自由表面效应等非线性因素,建立TLP系统的耦合动力学方程。采用变...由于地震、断层、滑坡和沉降等原因,张力腿平台(tension leg platform, TLP)下端的桩基可能发生错动。考虑平台本体有限位移、六自由度运动耦合、瞬时位置和瞬时湿表面、自由表面效应等非线性因素,建立TLP系统的耦合动力学方程。采用变步长龙格库塔算法编写了数值计算程序,得到了波浪作用下平台本体六个自由度运动响应和系泊张力响应。通过文献对比,验证了理论模型和计算程序的正确性。基于南海流花油田一年一遇的设计工况,计算得到桩基下沉0.1 m时16个工况下平台系统的动力响应的时间历程。以正常工况为基准,对比了不同工况中平台本体六个自由度运动、系泊张力的幅值和标准差,研究结果表明:桩基下沉对平台的六自由度响应和张力腿张力幅值产生明显的影响,但不加剧运动响应和张力响应的波动;桩基下沉会破坏平台系统原有的对称性,引起垂荡位移的较大恶化;桩基下沉会引起张力腿张力大幅增大,存在张力腿断裂和系泊失效的风险。展开更多
Mooring system failure can lead to largely different dynamic response of floating structures when compared to the response under the condition of intact mooring system.For a semi-submersible platform with taut mooring...Mooring system failure can lead to largely different dynamic response of floating structures when compared to the response under the condition of intact mooring system.For a semi-submersible platform with taut mooring system under extreme environmental conditions,the typical mooring system failure includes anchor line breaking failure due to the broken anchor line,and the anchor dragging failure caused by the anchor failure in the seabed soil due to the shortage of the anchor bearing capacity.However,study on the mooring failure caused by anchor failure is rare.The current work investigates the effect of three failure modes of taut mooring system on dynamic response of a semi-submersible platform,including one line breaking failure,two lines breaking failure,and one line breaking with one line attached anchor dragging failure.The nonlinear polynomial mooring line model in AQWA was used with integrating the load and displacement curve from the anchor pulling study to characterize the anchor dragging behavior for mooring system failure caused by the anchor failure.The offsets of the platform and the tension of mooring lines were analyzed for mooring system failure with 100-year return period.It is found that the mooring failure of one line breaking with one line attached anchor dragging is a case between the other two mooring failures.The traditional mooring analysis considering only the damaged condition with one line breaking is not safe enough.And the simple way of mooring analysis of two lines breaking is too conservative for the costly offshore engineering.展开更多
基金supported by the Fundamental Research Funds for the Central Universities,Dalian Maritime University,China(Grant Nos.3132019306 and 3132020116).
文摘This paper quantitatively studies the transient dynamic response of a semi-submersible production platform with the loss of one or several positioning mooring lines.A semi-submersible platform,production risers,and positioning mooring lines are all included in the numerical simulation.Increased motion of the semi-submersible platform,tension variation of the remaining mooring lines/risers and the risk of mooring line or riser clashing are all investigated through fully coupled time-domain analysis.Combined environmental loads are selected from irregular waves and the steady current varying from very rough to extreme sea conditions.Three dimension radiation/diffraction theories and Morison’s equation are applied to calculate first-order wave force and second-order mean drift force of floating semi-submersible platform.Nonlinear time-domain finite element methods are employed to analyze the behavior of mooring lines and risers.Results show that the failure of mooring lines seriously reduce the platform’s stability performance.The tension of the rest lines is also increased accordingly.Remaining lines which are closer to the failed lines will have larger tension increase to compensate.Line-Line distance provides practical information for the risk of clashing investigation.
基金Suppirted by the Programme of Introducing Talents of Discipline to Universities(B07019)
文摘This paper focuses on the research of a semi-submersible platform equipped with a DP-assisted mooring system. Based on the working principles of the DP-assisted mooring system and the model of the platform motion, a time domain simulation program is applied to analyze the impact, in the case of one line failure, on the platform motion, power consumption of the thrusters and the tension of the mooring lines. The results show that, under the 10-year wind dominant, a one line failure will have little impact on the tension of the mooring lines. When the failure line is windward, the power consumption will increase greatly with a weakened position of accuracy. However when the failure line is leeward, the power consumption will be reduced with a partly strengthened oosition of accuracy.
基金supported by the National Natural Science Foundation of China(Grant Nos.52268061,51808136,51878185)China Scholarship Council(No.201906660001)+1 种基金Guangxi Science and Technology Base and Talent Special Funds(No.2019AC20264)Guangxi Natural Science Foundation(No.2018JJB160058).
文摘Submerged floating tunnels(SFTs)are novel structures for transportation across long-and deep-strait regions.Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion,the risk of local anchor cable failure is high,which can result in the progressive failure of the entire structure.In this study,experimental and numerical investigations are conducted to analyze the dynamic behavior of an SFT with different mooring styles under local cable failure.A custom-designed cable failure device and the birth-and-death element method are used to simulate cable failure(i.e.,progressive failure)via experiments and numerical simulation,respectively.A physical-scale segmental model of an SFT with different mooring styles under anchor cable failure is developed in this study.A segmental and entire-length mathematical model is developed using the ANSYS program to perform the numerical simulation.The results of the segmental numerical and experimental models indicate good agreement.The dynamic response of an SFT with different mooring styles under cable failure is comprehensively investigated by investigating the effects of key parameters(wave period,buoyant weight ratio,and cable failure mechanism).Moreover,the progressive failure of the SFT under cable failure is investigated via a segment model test and a numerical simulation of its entire length.The present study can serve as a reference for the safer designs of the SFT mooring style.
文摘由于地震、断层、滑坡和沉降等原因,张力腿平台(tension leg platform, TLP)下端的桩基可能发生错动。考虑平台本体有限位移、六自由度运动耦合、瞬时位置和瞬时湿表面、自由表面效应等非线性因素,建立TLP系统的耦合动力学方程。采用变步长龙格库塔算法编写了数值计算程序,得到了波浪作用下平台本体六个自由度运动响应和系泊张力响应。通过文献对比,验证了理论模型和计算程序的正确性。基于南海流花油田一年一遇的设计工况,计算得到桩基下沉0.1 m时16个工况下平台系统的动力响应的时间历程。以正常工况为基准,对比了不同工况中平台本体六个自由度运动、系泊张力的幅值和标准差,研究结果表明:桩基下沉对平台的六自由度响应和张力腿张力幅值产生明显的影响,但不加剧运动响应和张力响应的波动;桩基下沉会破坏平台系统原有的对称性,引起垂荡位移的较大恶化;桩基下沉会引起张力腿张力大幅增大,存在张力腿断裂和系泊失效的风险。
基金financially supported by the National Natural Science Foundation of China(Grant No.51809165).
文摘Mooring system failure can lead to largely different dynamic response of floating structures when compared to the response under the condition of intact mooring system.For a semi-submersible platform with taut mooring system under extreme environmental conditions,the typical mooring system failure includes anchor line breaking failure due to the broken anchor line,and the anchor dragging failure caused by the anchor failure in the seabed soil due to the shortage of the anchor bearing capacity.However,study on the mooring failure caused by anchor failure is rare.The current work investigates the effect of three failure modes of taut mooring system on dynamic response of a semi-submersible platform,including one line breaking failure,two lines breaking failure,and one line breaking with one line attached anchor dragging failure.The nonlinear polynomial mooring line model in AQWA was used with integrating the load and displacement curve from the anchor pulling study to characterize the anchor dragging behavior for mooring system failure caused by the anchor failure.The offsets of the platform and the tension of mooring lines were analyzed for mooring system failure with 100-year return period.It is found that the mooring failure of one line breaking with one line attached anchor dragging is a case between the other two mooring failures.The traditional mooring analysis considering only the damaged condition with one line breaking is not safe enough.And the simple way of mooring analysis of two lines breaking is too conservative for the costly offshore engineering.
