浮体二阶运动下钢悬链式立管触地区动态响应分析

浮体运动是引起钢悬链式立管(steel catenary riser,简称SCR)动态响应和疲劳损伤的关键因素,目前研究SCR问题时,为简化计算往往仅考虑平台一阶运动,忽略二阶运动影响。而实际上不同浮体结构的二阶运动响应特征明显,拟以SCR服役张力腿平台(tension leg platform,简称TLP)为例,探讨浮体二阶运动对SCR触地区动态响应的影响。建立考虑海床刚度退化的管土作用模型以改进现有的CABLE3D RSI程序,通过编写程序接口,将有限元分析得到的平台实际运动响应导入,研究平台不同运动作用下SCR触地区的位移、动力响应及疲劳分布情况。根据波流作用方向将TLP二阶慢漂运动分为近端和远端漂移两种工况,发现二阶运动下立管与海床的作用范围会增大,且触地区不仅发生高频小幅振荡运动,同时伴随低频大幅运动响应;平台远端漂移时,管内张力敏感程度高,而近端漂移时触地区的弯矩显著增大,都会不同程度提高触地区的疲劳损伤率。研究可为服役不同浮体的SCR响应预测与疲劳分析提供参考和借鉴。     

Non-linear restoring forces of an offshore platform

The method of calculation of non-linear restoring forces presented in this paper is simple, concise and feasible to apply easily in the calculation of restoring forces of platforms in order to simulate motion responses of offshore platforms in the time-domain. In this method, hydrostatic restoring forces and moments are related to the translational and/or rotational displacements. Calculations of non-linear yaw, roll and pitch restoring moments are based on the catenary type of moorings. Although the method presented here is a simple one, it is capable of the calculation of restoring forces for use in the time-domain motion simulations of offshore platforms, with an acceptable degree of accuracy when the numerical simulation results were compared with the experimental measurements.     

火灾作用下海洋平台结构响应分析

结合BZ28-1南井口平台导管架,建立了海洋平台结构有限元计算模型。采用弹塑性分析方法,并应用温度升高时钢材的非线性应力/应变关系,采用火灾的标准温度-时间曲线建立平台结构温度随时间的变化模型,基于能量守恒原理建立热传导微分方程,计算热传导和对流对结构温度的影响,分析得到受火区域构件的温度场。依据钢材性能随温度升高的变化,分析火灾荷载下平台结构的响应。火灾发生时,平台结构中的构件在火温的作用下,温度逐渐升高,虽然作用在结构上的荷载不变,但由于钢材的弹性模量和屈服强度都急剧下降,使平台结构的承载能力下降;当温度上升到600℃以上时,平台结构就形成足够数目的塑性铰,使结构达到极限破坏状态。通过计算分析表明,当火灾作用6 min后,着火房间构件发生严重屈曲,但平台结构整体性能保持良好;当火灾作用22 min后,受火区域构件都发生了较大的变形,引起平台结构的毁损和倾覆。     

海上油井管柱弯折及工程处理

海上石油开发油井建设中，发生了井柱弯折现象。对工程处理中可以采用的小沉箱、大沉井、定向井、人工切割开洞等方案进行了介绍和比较，最后论述了采用的方案及原因。     

海洋导管架平台随机响应混合分析方法

采用将结构的解析分析和数值求解方法相结合的固定式海洋平台随机响应混合求解方法，考虑波浪－结构相互作用和基于最小二乘法原理的非线性曳力的影响。采取两个步骤，第一步进行与结构有关的特征值分析；第二基于谱方程进行响应估计，进行海洋平台的线性和非线性数值分析。     

Multi-component seismic response analysis of offshore platform by wavelet energy principle

A wavelet energy method is presented to search the critical incidence of earthquake excitation in a multi-dimensional seismic response of offshore platforms. The total effective energy and the instantaneous effective energy input rate of an earthquake can be obtained by wavelet transformation to predict the critical incidence of the earthquake and then the maximum dynamic response of the platform can be calculated. The critical incidence is determined using this method for an actual platform and a group of single degree-of-freedom systems. Numerical results show that the application of wavelet transform in a multi-dimensional seismic response of structures is convenient and reliable.     

海洋平台结构动力响应优化设计与灵敏度分析

研究了海洋平台结构动力响应优化设计以结构动力响应的灵敏度计算方法。给出了结构稳态频率响应和瞬态时程响应的灵敏度分析算法，并通过数值试验讨论了瞬态响应灵敏度分析算法的精度和差分法中变量摄动量的影响。在JIFEX软件中实现了结构动力响应灵敏度计算，建立海洋平台结构优化模型和求解方法。数值算例表明了本文方法和程序的有效性。     

极限波浪作用下半潜平台运动响应时域数值模拟

针对一座工作水深为500 m的半潜式海洋平台,运用时域耦合分析方法,计算其在极限波浪作用下的运动响应。通过比较平台在两种不同形式极限波浪(即畸形波和"三姐妹"波)作用下的运动响应,分析两种不同形式的极限波浪对平台运动的影响。同时通过分析畸形波的参数对平台运动幅值的影响,确定平台运动响应对畸形波参数的敏感性。分析结果表明:极限波浪在聚焦点处波高最大,当平台恰好位于聚焦点时,对平台来说最危险;畸形波的波峰值是影响平台运动的最主要参数,在平台初期设计中要考虑工作海域中极限波浪可能达到的最大值;在波峰值相同的条件下,平台运动的最大值随着畸形波的谱峰周期和有义波高的增加而增加。     

Premature refusal of large-diameter,deep-penetration piles on an offshore platform

Open-ended pipe piles are commonly driven into the seabed to support offshore platforms. This paper presents a case of practical offshore driven pile installation experiences associating with premature refusal. Pile drivability and capacity are analyzed using sufficient driving records. Dynamic loading tests were performed three months after the driving in order to determine the pile capacity after refusal. The test results are detailed in this paper compared with back analysis of measured pile driving records. Empirical equations are provided to predict soil resistance during driving and after setup according to the driving records and dynamic loading tests. Analyzing this practical engineering case is hoped to lead to a better understanding of pile driving, especially when premature refusal occurs. The sufficient details of the engineering data in this paper are also expected to enrich the engineering experience and literature of offshore piles in offshore engineering.     

基于多源卫星遥感的渤海海上油气平台识别

针对海上油气平台信息不足的问题,开展多源卫星遥感的油气平台识别方法研究。基于Landsat-8光学遥感影像(2018—2021年)应用阈值分割法、K-means分类法和最大似然分类法分别识别出渤海海域油气平台136座、166座和113座;基于Sentinel-1 SAR影像(2018—2021年)应用阈值分割法识别出油气平台338座;对上述结果进行决策级融合,识别出渤海油气平台428座。利用ZY-3高分辨率影像对融合方法的识别结果进行验证,结果显示识别油气平台的正确率达到85.2%,错判率、漏判率分别为10.9%和3.9%;油气平台位置与相关文献和公开资料一致。研究结果表明,决策级融合方法能够实现海上油气平台的有效判别,具有推广、应用价值。     

岛礁附近浮式平台运动响应特性数值分析

利用基于开源平台Open FOAM自主开发的船舶与海洋工程水动力性能求解器naoe-FOAM-SJTU,数值模拟了近岛礁环境下规则波的演化特性以及带有系泊系统的浮式平台在相应波浪作用下的水动力性能。对于平台的水动力性能的研究发现,仿真结果与试验结果在平台自由衰减运动固有周期及RAO(response amplitude operator)方面吻合良好。对于波浪在近岛礁地形下的演化现象的研究,分析了波浪演化不对称性特性的成因,并分别给出了不同参数下波浪在地形上爬升时演化的具体特性,对于波高变化及波浪演化的频率成分进行量化的探究。研究发现,波浪周期越大,波高变化越明显,演化的非线性现象越明显,且波浪随着传播距离的增大演化出的阶数也在增大。     

海洋平台结构的最新研究进展 第9届ISOPE大会报告综述

分9个专题对第9届ISOPE大会报告有关海洋平台结构的最新研究动态进行了评述和总结,并结合我国海洋石油工业的发展现状提出了一些建议,供我国产业部门和有关高校与研究机构参考。     

海洋石油平台溢油风险评价研究

通过层次分析法,系统分析了我国钻井平台及生产平台的溢油风险因子,初步建立了该类设施的溢油风险评价指标体系,并运用多级模糊综合评级模型对目标设施的溢油风险进行综合评价。利用该评价方法对渤海某一钻井平台进行溢油风险分析,结果表明该平台溢油风险等级较低,风险因子中海区环境及平台疲劳老化程度的风险相对突出。该评价方法可及时判断目标设施的溢油风险等级,为减少、预防各类平台溢油事故提供技术支持。     

非灌浆导管架平台异常振动的测试分析及故障诊断

通过对平台在风浪作用下的振动测试分析,发现了直立式非灌浆桩腿导管架平台在海底冲刷条件下发生异常振动的原因是导管架与桩之间存在较大的相对运动,以至于在风浪较大时发生碰撞。因而,结构的动力特性和动态响应都与设计结果不一致。在非极值海况条件下,平台的振动超出了设计预测值,并提出了治理和设计建议。     

偏航工况下海上浮式风力机基础运动响应及锚泊载荷影响分析

海上浮式风力机受风、浪、流等外部载荷影响,运营期间经常处于偏航工况,给风力机基础运动响应和锚泊载荷带来重要影响.基于经典叶素动量理论及势流理论,建立海上浮式风力机水—气动力耦合分析模型,对在非定常风、不规则波浪联合作用下,风力机偏航时基础运动响应及锚泊载荷等进行分析.研究发现,额定风速工况下,风力机偏航对平台纵荡和纵摇运动影响较大,偏航30°时纵荡和纵摇平均值比偏航0°时分别下降20.68％和37.36％,垂荡运动响应受风力机偏航影响较小;锚泊载荷变化趋势与平台运动及锚链布置有关,平台纵荡对锚泊载荷影响较大,偏航30°时锚链#1有效张力平均值比偏航0°时下降12.98％.     

Recent developments in offshore rig/ platform evacuation

During severe storms, evacuation systems for offshore rigs and platforms currently in use have proven themselves to be inadequate. Typically, during deployment of a lifeboat, it is often damaged to the point of not being seaworthy before it reaches the ocean surface. This is especially the case for cable-launched boats where a pendulum-like motion of the craft on its cables is often set up. It is less of a problem for free-fall lifeboats. Even when a craft reaches the ocean surface intact, high winds and waves can drive it back against the rig/platform structure. This paper describes the state-of-the-art of evacuation. It focuses on two new systems being developed by the authors in Newfoundland, Canada.     

Two dimensional responses of fixed offshore platform in waves

Responses of a four-legged offshore platform to wave forces are analysed by taking account of one torsional motion around the vertical axis which passes the centre of gravity of the structure, and two translational motions in the horizontal plane. Applying the spring-mass system with one degree-of-freedom to each mode of motion, a calculation method for predicting resultant dynamic displacements of the topdeck is developed. Both the inline force and the transverse force are considered as external forces. The calculated results are found to agree with experiments. Furthermore, the influence of seven important factors on the dynamic response is examined by the calculations. It is shown that the combination pattern of the direction factor of the transverse force is of importance in dynamic analysis.     

Study on nonlinear dynamic characteristics inherent in offshore jacket platform using long-term monitored response of ice-structure interaction

This paper proposes a method to structurally identify inherent dynamic characteristics based on long-term monitored acceleration data of nonlinear offshore platforms under sea-ice excitation. Not all the inherent characteristics can be excited due to the randomness of ice loading and its limited bandwidth. However, the long-term monitored data can reflect most of the conditions of sea-ice excitation. The change of natural characteristics of the platform under ice loads can be identified by analyzing of long-term monitored data. A nonlinear system of two-degree-of-freedom (2DOF) is simulated to identify dynamic characteristics and verify the effectiveness of the proposed method. The method is applied to analyze the acceleration data caused by ice-induction at a jacket platform in Liaodong Bay. The inherent characteristics of the structure can be identified and its variation under different ice-load intensities is summarized.     

基于海洋结构谱响应波浪载荷参数识别

波浪谱是研究随机波浪的主要方法,也是海洋工程设计的重要依据.介绍在线性波情况下圆柱形结构响应施加了白噪声之后频域内的载荷识别方法,根据谱分析的方法,考虑线性波前后桩腿相位差的影响,比较单个频点反演与采样频率内利用对频率取矩法反演结果的准确度,结果表明在已知波浪谱的情况下利用矩来进行反演识别有明显的优越性.     

Truss Spar平台在波流联合作用下运动响应预报方法比较

基于细长体水动力模型比较了Truss Spar平台在波流联合作用下运动响应预报的三种方法。分别采用波流耦合、速度叠加及力叠加计算Truss Spar平台在波流联合作用下的水动力载荷,根据流场水质点运动规律和Truss Spar外部形状特点,分段高效计算水动力载荷。利用Runge-Kutta-Fehlberg方法求解刚体非线性运动方程得Truss Spar在波流场中的运动响应。研究结果表明力叠加法所预报的Truss Spar纵荡和纵摇运动明显大于其他两种方法的相应运动响应预报结果,而波流耦合法与速度叠加法所预报的纵荡与纵摇运动响应幅值相当,三种方法所预报的垂荡运动响应的大小取决于具体波流参数。