Research on technology of automatic welding machine and procedure for pile pipes of offshore jacket platform

Because of the high requirement of quality,vile working environment and great difficulty of automatic welding,MMAW is usually adopted for the welding of the platform jacket and the pile pipe.Its low efficiency and hard working is one of the choke points for construction progress. In this article,an up-to-date technology for platform pile pipe welding was introduced. Cored with FCW-S and combined with the characters and requirements of platform construction,the special automatic horizontal welding equipment and process were developed. Further more,the offshore application were introduced too.

Parametric Study on the Effects of Pile Inclination Angle on the Response of Batter Piles in Offshore Jacket Platforms

近海夹克衫类型平台被纳入海床由长击打堆积。在这份报纸，源于有限元素分析，对试验性的数据验证了，被用来学习堆积倾斜角度的效果，并且它和堆积的几何性质和支持夹克衫平台的使倾向的堆积的行为上的包围土壤的 geotechnical 特征的相互作用。结果证明倾斜角度是影响行为的主要参数之一一近海堆积。我们在垂直方向在最大的 von 协定压力，最大的 von 协定有弹性的紧张，最大的排水量向量和，在水平方向的最大的排水量，和最大的排水量上调查了倾斜角度的效果。堆积似乎有约 5 的倾斜的操作上最佳的度为一个 NACA6409 翅膀的力量，速度，和排水量解决在一 40，和 20 ?

Optimum Design of Jacket Platforms Considering Structure-Pile-Soil Interaction

This paper proposes an optimum design model for the offshore jacket platform considering multidesign criteria, multi-design constraints and the structure-pile-soil interaction, and gives an optimum design procedure in which the proposed optimum design model is used together with structural analysis software SAP91 and optimum algorithm software OPB1. The Chengbei (#)11 offshore platform, which lies in the Shengli oilfield, is designed by use of the above optimum design model. The results show that the optimum design model is stable, and it depends on neither the optimization algorithm nor initial values of design variables. All values of the objective function converge to the same minimum value, and the speed of convergence is high, showing that the proposed optimum design model is reasonable.

高强灌浆材料结合卡箍在导管架受损构件加固中的应用

以南海某海域一施工船与四桩导管架基础发生碰撞为背景,结合当前研究对导管架受损区域的承载力进行分析,计算得到受损截面凹陷处的轴向承载力和极限弯矩。简述海洋工程领域中受损构件的加固修复方法,探讨卡箍技术的理论研究现状及其在实际工程中的应用现状。基于典型灌浆卡箍修复技术提出一种采用80 MPa高强度灌浆材料结合卡箍技术进行加固修复的新方案,并采用有限元软件对加固后的组合结构进行数值模拟。仿真结果表明,该组合结构可有效改善导管架受损区域受力状况,提高结构的承载力。简述该方案的施工流程,以期为实际工程提供参考。

特异型海上结构物拆除后运输固定设计分析

考虑到海上油气平台弃置拆除已逐步产业化,待拆除结构物的形式多种多样,对渤海、南海、泰国湾等海域已完成拆除的结构物进行归纳,总结拆除特异型结构物运输固定设计的流程、结构物特点、专用设计方法。如采用易脱桩导管架装船运输时设计的新工装,可满足多种卸船方式,可有效解决易脱桩的难题;含易燃易爆残留物的大型储罐利用数值模拟使用非焊接固定法,可解决不能动火的难题;稳性差的结构物运输时设计的阵列式结构可缩短工期,解决稳性差的结构在运输中易发生倾覆、单根桩受力过大的技术难题,所总结的方法均在工程实践中取得了良好的实施效果且得到了权威机构的认可。

Investigation on the Effect of Geometrical and Geotechnical Parameters on Elongated Offshore Piles Using Fuzzy Inference Systems

Among numerous offshore structures used in oil extraction, jacket platforms are still the most favorable ones in shallow waters. In such structures, log piles are used to pin the substructure of the platform to the seabed. The pile＇s geometrical and geotechnical properties are considered as the main parameters in designing these structures. In this study, ANSYS was used as the FE modeling software to study the geometrical and geotechnical properties of the offshore piles and their effects on supporting jacket platforms. For this purpose, the FE analysis has been done to provide the preliminary data for the fuzzy-logic post-process. The resulting data were implemented to create Fuzzy Inference System （FIS） classifications. The resultant data of the sensitivity analysis suggested that the orientation degree is the main factor in the pile＇s geometrical behavior because piles which had the optimal operational degree of about 5° arc more sustained. Finally, the results showed that the related fuzzified data supported the FE model and provided an insight for extended offshore pile designs.

Finite Element Simplified Fatigue Analysis Method for a Non-tubular Joint of an Offshore Jacket Platform

This paper proposes the finite element simplified fatigue analysis method for fatigue evaluation of the composite non-tubular joint structure of an offshore jacket subjected to wave loads. The skirt pile sleeve of the offshore jacket, which had been in service, was taken as an example of the non-tubular joint structure. SACS software was used for global analysis of multi-directional wave loads for the jacket platform, and ALGOR software was used to build a finite element model, perform finite element analysis, post-process stress results for acquiring the stress range, and perform fatigue evaluation. The analysis results indicate that the extreme stress range is within the allowable stress range and meets the requirements of DNV code. That means the simplified fatigue analysis method is effective and can be used in fatigue design for the non-tubular joint structure of an offshore jacket.

Investigation on Cutting Stability of Jacket in Decommissioning Process

Jacket cutting operation is one of the most complicated and highest risk operations in the process of decommissioning offshore piled platform, the security and stability of which must be assured. In this paper, the current research on offshore structure removal and jacket cutting is introduced, on the basis of which the types of load along with the load calculation method are determined. The main influences on the stability of a jacket in cutting are analyzed. The experiment test plan is drawn by using orthogonal testing method, and the formula of critical load during the cutting procedure is deduced by differential evolution algorithm. To verify the method and results of this paper, an offshore piled platform to be decommissioned in the South China Sea is taken for an example, and the detailed schedule for jacket cutting is made with the three-dimensional finite element model of the jacket established. The natural frequency, stress, strain and stability of the jacket during cutting process are calculated, which indicates that the results of finite element analysis agree well with that of the deduced formula. The result provides the scientific reference for guaranteeing the safety of jacket in cutting operation.

Reliability-Based Design for Jacket Platform Under Extreme Loads

In this paper, reliability analysis for the offshore jacket platform with the interaction of structure- pile- soil under extreme environmental loads is carried out. The inherent uncertainties of the environmental load, foundation soil, platform itself, and calculating models are evaluated. The action of extreme loads on the offshore platform is modeled as a function of extreme wave height. The system capacity of the whole platform is determined by nonlinear pushover analysis, and the relevant probability property is obtained by the simulation method. The reliability model for the whole jacket platform is described as the relationship between the load and resistance based on the offshore design codes. The reliability of whole platform is calculated by the analytical method and the importance sampling method on the basis of a case study for a tripod jacket platform.

海上风电导管架式基础钢管桩沉桩技术

以广东海域某海上风电场工程为例,分析了海上风电导管架式基础大直径、长钢管基础桩沉桩施工难点及关键技术,对基础桩沉桩施工流程进行了详述。通过应用特殊设计的负压式稳桩平台、夹持式起桩器及内插式送桩器等设备设施,并采取合理的施工工艺,有效地降低了恶劣海况对施工的影响,保障了沉桩精度,提高了沉桩施工工效及质量,可供类似工程借鉴。

海上风机导管架基础疲劳分析

导管架基础因其整体刚度大,适应范围广等优势已经成为越来越多海上风电场的首选基础形式。目前对于该基础的研究多关注于承载与变形特性,对于其疲劳特性的研究相对较少。同时,针对风机基础的疲劳分析往往将桩−土系统简化为土弹簧,忽略实际的桩−土相互作用。建立了四桩导管架基础与海床相互作用三维数值模型,并通过离心模型试验进行了验证,在此基础上提出了充分考虑桩−土相互作用的导管架基础全时域疲劳分析方法。分别研究了桩−土相互作用,风浪荷载耦合,水平加载偏角等对导管架结构疲劳损伤的影响。主要发现有:忽略桩−土相互作用会严重低估导管架结构的疲劳损伤,平均低估约40%;而对于下部斜支撑节点的疲劳损伤的低估在极端工况下甚至可达90%。风荷载在导管架结构疲劳损伤中占主导地位,远大于波浪荷载影响。水平风浪荷载沿对角线加载会比沿边长方向加载产生更大的位移响应,但相应的疲劳损伤较小,约为沿边长加载的70%。

水下插桩定位系统在导管架吊装中的应用

针对海上导管架吊装水下插桩到海底已有钢管桩内的作业难点,通过使用高精度定位设备、罗经、姿态仪和无线网桥,组建集测量导管架位置、高程、方位和姿态于一体的三维定位系统,接入定位软件中,实现实时显示导管架的位置、高程、方位、姿态和导管架桩腿插尖分别距每个海底钢管桩的平面距离和垂直距离,用于指导导管架吊装作业。在广东阳江某海上风电项目中,将该定位系统应用于风机导管架吊装作业中,实现了数字化和可视化作业指导,快捷地完成吊装作业,对后续类似项目具有参考意义。

海上风电螺旋桩侧向承载能力分析

The rapid development of offshore wind power and the need to move to deeper sea areas while reducing costs per kilowatt necessitate the employment of a new jacket and helical pile combination.This new combination combines the advantages of both jacket structures and helical piles and provides a superior bearing capacity and installation efficiency compared to conventional pile foundations.Foundations account for 25%-34%of the overall cost of construction,but the use of this new foundation would be highly significant for the further development of offshore wind power.This study presents numerical results for the horizontal bearing capacity when horizontal displacement is applied,focusing on the bearing capacity and characteristics of the helical pile jacket foundation as well as the differences between the bearing mechanisms and failure modes of normal pile and helical pile types.ABAQUS model parameters are obtained through trial calculations based on actual engineering data,and the finite element model(FEM)is validated using data from a model experiment.Subsequently,different FEMs are established,and numerical results are compared and presented.Through a comparison between a normal pile jacket foundation and a helical pile jacket foundation with different helical blade numbers,the differences in the bearing mechanisms and failure modes are revealed.The failure of the normal pile jacket foundation is instantaneous and sudden,whereas that of the helical pile foundation is incremental and accumulative.These data highlight the most significant contributions and vulnerabilities of the one-pile side of the foundation and suggest that the addition of blades on the one-pile side is the most effective way of improving the foundation’s bearing performance.In addition,the interaction between the compression side and tension side is analyzed in relation to differing the relative magnitudes of their bearing capacities.

板沙地质斜桩导管架施工方法探究

中国海上风电作为绿色能源的重要一支,现已进入大规模化发展阶段。如果把海缆类比成海上风电场的血管和神经,那么,海上升压站则可以比作整个风电场的“心脏”。所有的风力发电机发出的电能在此汇集,通过送出海缆连接到陆地上的电网,输送给千家万户。作为海上升压站支撑的主要结构件导管架的施工,更是整个风场施工的重点。文章主要介绍在中国南海海域铁板沙地质情况下,斜桩导管架的施工方法。主要研究了针对铁板砂地质,小桩腿自沉零入泥情况下采用震动锤加液压打桩锤联合施工的施工方案。南海海域某项目采用先安放导管架后沉桩的工艺,在小桩自沉基本为零的情况下,采用此方法后安全、高效的完成现场施工。

黏土中海上风电超大型吸力桩基础沉贯安装分析

吸力桩基础安装前需要进行沉贯和结构屈曲分析。针对国内首个全场采用吸力式基础的大型风电场,提出一种在黏土中超大型吸力桩沉贯阻力改进计算方法,在现有规范基础上,考虑桩侧向土的扰动效应,引入黏性土灵敏度,对桩侧土阻力进行折减。基于安装海域实测海床土壤参数,对吸力桩导管架基础沉贯阻力及所需压差进行计算,通过与DNVGL规范和实测值对比,验证改进计算方法的准确性,基于此方法对安装时可能需要临时顶起的阻力进行分析;进一步使用有限元法对两种吸力桩顶盖进行数值建模,开展吸力桩在安装沉贯及临时顶起过程顶盖屈曲特性研究。结果表明:随着贯入深度的增加,吸力桩导管架基础的沉贯阻力逐渐增大,DNVGL规范计算得出的沉贯阻力与所需压差较大,而改进方法计算结果与实测值更为接近;DNVGL规范计算得出的顶起所需压差整体上明显大于改进方法计算值;吸力桩在达到沉贯以及顶起所需最大压差时,顶盖处于弹性阶段,不会发生屈曲破坏。

典型海上升压站导管架基础施工技术探讨

海上升压站在风电场中起着升压功能,将所有风机发的电汇聚并对外输送至陆地,升压站基础为上部组块提供牢固根基,保证上部组块各设备正常运行。基础形式主要为导管架结构,不同导管架结构类型具有不同的施工技术,对导管架基础类型与施工技术的研究具有重要的价值。文章主要从升压站导管架基础类型分类以及对应的施工技术进行研究,并对不同的施工工艺技术进行重点对比分析。随着海上风电场向深海发展,不受水深限制的后水下桩型导管架基础优势越来越明显。基于其施工工艺特点,文中重点对其导管架调平与水下灌浆施工工艺提出优化建议,对后水下桩型导管架基础施工技术发展提供借鉴意义。

海上风电导管架基础沉桩定位平台应用

通过对海上风电导管架基础沉桩定位平台结构及使用效果进行综合对比分析,总结了浮式、坐底式以及负压桶式3种高精度沉桩定位平台的优缺点,提出了不同沉桩定位平台在适应范围、船机设备配置、工效等方面的合理化建议,可为今后海上风电导管架基础沉桩施工提供借鉴。

导管架大直径短桩竖向承载力CPTU方法应用分析

[目的]目前,我国的海上风电工程中,随着工程开发逐步走向深远海,风电机组最常用的基础结构是桩基础,而最常用的上部结构为导管架结构,两者的结合构成了风电机组的基础支撑体系。在一些深水的浅覆盖层地区,大直径导管架基础的应用需求尤其强烈,而下部桩基础的设计直接决定了方案的可行性及结构的安全性,为验证导管架大直径短桩桩基承载力问题,提出采用孔压静力触探试验(CPTU)的计算方法应用。[方法]通过API规范推荐的CPTU计算方法中的UWA-05方法,进行承载力计算,进一步结合广东某风场高应变实测数据与公式计算结果进行对比分析,并对公式本身端阻差异较大的情况进行了参数拟合。[结果]结果表明:采用CPTU方法计算导管架大直径短桩桩身侧阻时,与实测数据拟合度较好。导管架大直径短桩难以形成有效土塞,在采用CPTU方法计算端阻时,建议仅考虑端部环面积。[结论]由此采用CPTU方法计算导管架大直径短桩承载力是可靠的方法,但在使用时候建议结合试桩数据对比验证,为后续深远海风场利用CPTU进行大直径短桩承载力计算应用提供借鉴。

海上风电四桩导管架基础风致疲劳数值分析

文章采用有限元软件ANSYS对四桩导管架基础进行风致疲劳数值分析,整个导管架结构均采用八节点shell181壳单元模拟进行精细化建模计算。疲劳损伤计算采用热点应力法获取结构应力幅值,之后利用Miner线性累积损伤理论对结构疲劳寿命进行评估,最终累积疲劳损伤为0.61,满足设计要求。对热点应力法求得的应力与直接提取危险点表面应力进行对比,结果发现,前者小于后者,且更接近真实值。针对厂家提供的等效疲劳荷载、谱疲劳荷载分别进行四桩导管架基础的疲劳计算,结果发现谱疲劳与等效疲劳相比结果偏小。通过热点应力法对导管架基础进行疲劳计算,在保证安全的前提下能有效节省工程成本。

三筒吸力桩导管架建造工艺与精度控制

海上风电场三筒吸力桩导管架,可分为过渡段、导管支架、吸力桩三大部分。本文探讨了这三部分和总组的建造工艺流程以及建造过程中的精度控制要点,为类似项目提供参考。