【作者】 王延林；

【导师】 岳前进；

【作者基本信息】 大连理工大学 ， 工程力学， 2011， 博士

【摘要】 海洋平台是海上石油开采的主要装备。尽管经过了半个多世纪的发展,海洋平台的结构设计理论与技术已经日趋成熟,但是仍不能很好地满足海洋石油的安全与经济性的开发需求,特别是对于极端海洋环境下的特殊海洋工程结构设计,如寒区与深水的海洋平台设计理论仍不成熟。对于复杂海洋工程结构,采用常规的数值模拟与模型实验等方法也无法满足设计分析的需要。利用已经建造的平台进行原型结构测量,可以获得真实的荷载及结构响应信息,为结构的设计与分析研究提供了新的途径。原型结构测量的方法在目前海洋工程结构设计分析中也得到越来越广泛的重视,其不仅可以为结构设计与评价提供信息,也可以指导现役平台的安全保障与风险预警等工作。然而,利用现役海洋平台进行原型结构测量并开展结构设计分析,也存在一些理论与技术问题需要解决。比如,如何在实际的平台上安装测量传感器,即进行原型结构测量设计,如何在现场获取连续与完备的数据,如何对实测数据进行分析与评价等。因此开展基于现场原型结构的测量分析,一方面需要综合的的结构分析方法,例如理论分析、数值分析及室内模型实验等辅助方法,才能设计出有针对性的原型测量方案,进而获取有效的测量数据；另一方面,需要借助当今先进的电子、通信与计算机技术,采用先进的监测手段,通过长期不间断的现场原型监测,才能在现场原型结构上获取连续与完备的测量数据；此外对于测量数据进行分析评价,回归到结构设计等问题上,又需要借助数据统计分析、结构数值分析等综合技术。因此,现代结构分析技术与结构监测技术的发展,为基于原型测量方法的特殊结构设计分析方法的发展提供了很大的帮助。实际上,不仅是海洋平台结构,其它工程结构的原型测量方法与技术也是目前研究的热点问题。本文重点针对抗冰平台结构设计与运行中所关心的问题：确定冰荷载问题、确定结构冰激振动引起的失效模式、风险预报与预警问题以及新概念抗冰结构的设计性能评价问题,开展了原型结构测量与分析评价的研究。利用渤海辽东湾的多座抗冰平台建立了比较完善的抗冰结构设计与分析评价的研究基地。本文的研究虽然是基于渤海抗冰导管架平台的研究,但同时对其它工程结构的原型测量研究也具有参考价值。本文主要研究内容如下：1.抗冰结构原型测量技术研究自上世纪九十年代初,我国在渤海建立了十几座导管架式抗冰平台,大连理工大学对其中多个平台进行了冬季抗冰结构的原型测量研究。本人在论文期间,参加了五个冬季的现场监测工作,并对抗冰结构现场监测系统进行了改进与完善；根据抗冰结构所关心的问题,包括冰荷载问题,冰振平台失效风险和安全预警问题以及结构设计评价问题,设计了共享的现场监测系统。所监测的信息包括冰力信息,冰荷载参数信息(冰厚、冰速),结构响应(应变,加速度)信息等,并对测量中的这些关键技术进行了深入的分析和研究,为进一步的面向渤海抗冰结构的原型测量研究的开展奠定了基础。2.冰荷载的原型测量研究冰荷载是冰区海洋平台结构的控制荷载,也是制约抗冰结构设计的主要不确定因素。由于冰荷载是冰与结构相互作用的破坏过程形成的,目前还缺少成熟的理论进行数值模拟,同样采用模型实验也缺少相似理论为依据。因此利用真实结构的原型测量方法确定冰荷载是目前冰荷载研究的主要手段,得到国际上的广泛重视。本文通过对渤海真实的直立结构和锥体结构的冰荷载的直接测量以及同步的结构响应和海冰参数的原型测量,获得了较为完备的建立动冰力模型的数据；通过冰荷载间接测量方法,获得了较为准确的极值冰力数据。该工作为动冰荷载及极值冰荷载问题的研究奠定了基础。3.面向抗冰结构冰振风险的原型测量、分析与预警由于冰荷载,特别动冰荷载研究的不成熟,导致了在较长的一段时期内,抗冰结构设计存在诸多的不确定性,包括结构冰振失效模式的不确定,从而导致冰区海洋平台存在较大的风险隐患。本文基于渤海辽东湾的多座抗冰平台,面向抗冰结构的冰振风险问题,进行了原型测量、分析与预警方法的研究。其中设计并建立了的面向冰振失效风险问题的现场原型监测系统；基于监测数据建立了平台冰振响应的预测模型,对渤海在役抗冰平台的风险预警标准及流程进行了探讨,为类似抗冰结构冰振风险分析与预警等相关工作提供了借鉴和参考。4.面向新型抗冰平台抗冰设计性能的原型测量、分析与评估抗冰结构设计是渤海边际油田开发的研究热点,近些年提出了多种抗冰振平台的设计理念,包括破冰锥改变冰荷载技术,整体隔振技术等。如何检验和评价这些抗冰技术成为一个比较关键的问题。本文基于上述目的,提出了面向抗冰设计性能的原型测量与分析评价的方法,该方法可以很好地弥补数值分析与室内模型试验方法中存在的缺陷和不足,对于抗冰结构设计研究具有很高的参考价值。本文对两种新型的抗冰平台的抗冰性能进行了原型测量、分析与评估的研究,包括：①对简易桶基抗冰平台的加锥减振设计进行了原型监测,剖析了加锥减振设计对冰荷载及冰振响应的影响,对减振设计进行了评估；②针对新型的独腿抗冰平台的抗冰性能进行了原型监测系统的设计与现场实施,基于实测数据对该平台的抗冰设计性能进行了分析与评估,对抗冰设计中存在的优缺点进行了探讨。最后对全文进行了总结与展望。更多还原

【Abstract】 The offshore platform is a very important facility in the offshore oil exploitation. There are still many uncertainties in the design of offshore platform, which had induced many security risks in the service period of it, although the design of it has been developing for more than half a century. The offshore platform is a very complex engineering structure which usually suffered from various complex loads. The conventional methods, such as theoretical analysis, numerical simulation and model test, can not solve satisfactorily the existing problems of the offshore platform in service. Thus, the prototype measurement is needed for the real offshore platform in field, through which we not only can get the real load and response information to verify the problems in the design and service process, but also can provide early warning information on the risk of the structures. Therefore, the prototype measurement methods of offshore platform structures have attracted increasing attention widely in recent years.However, there are still many theoretical and technical problems in the prototype measurement on a real complex offshore platform, such as how to design the prototype measurement system, how to obtain the desired and complete data in field, how to deal with and use the real measured data and so on. Therefore, the prototype measurement is designed specifically for each project using the theoretical analysis and numerical simulation methods and some experiences. Secondly, we need to solve the measurement technical problems in the prototype measurement according to the realistic conditions. Sometimes, we need to monitor the prototype structure continuously so as to capture the desired information. Finally, analysis and evaluation of the measured data provide a guide of the design and operation of the structures. The modern monitoring technologies and the numerical analysis methods are very helpful to the researches on the prototype measurement method. Actually, researches on the prototype measurement method and related technologies are very hot not only in ocean engineering but also in other engineering.This dissertation deals with the prototype measurement method of the service platform for solving some uncertain problems in the design and operation process of the platforms in Bohai. The prototype measurement method has been used for various problems including the ice force problem, ice-induce vibration risks analysis and warning, the evaluation of the ice-resist design. The studies in this dissertation are also useful for other engineering prototype measurement research, although the work is based on the offshore jacket platforms. The main works of this dissertation are as follows:1. The research on prototype measurement technologiesMore than a dozen ice-resist offhore jacket platforms were established in Bohai Sea of China since the early 1990s. Much prototype measurement research work had been taken on these platforms by Dalian University of technology. I have joined the prototype monitoring work for five winters and improved the on-site monitoing system. A shared prototype monitoring system was designed for the problems induced by ice, such as ice force problem, ice-induce vibration risks analysis and warning, the evaluation of the ice-resist design and so on. Furthermore, more analysis and research work had been taken on the core technologies of prototype measurement on ice-resist strcutures. These work built a nut foundation for further prototype measurement research on ice-resist strucutres in Bohai Sea.2. The research on prototype measurement of ice forceThe ice force is the dominant force for offshore platform in cold regions, and also is the main uncertainties in the ice-resist structure design. The ice force is produced by the ice-structure interaction process. There is not a very well-developed method for numerical simulation and model test of ice force. Therefore, the research of ice force through prototype measurement method is the main primary means in ice force research and widely adopted in many countries. In this chapter, complete measured data for the establishment of dynamic ice force and extremum ice force, were obtained through direct ice force measurement, indirect ice force measurement and ice parameters measurement on the prototype structures in Bohai.3. The research on ice-induce vibration risks through prototype measurement methodDue to the behindhand research on the ice force, especially the dynamic ice force, the offshore platform is very dangerous in cold regions. As there are many uncertainties in the design of the ice-resist platforms including the uncertainty of the failure mode of ice-induced vibration. In this chapter, the failure mode and failure criterion of the platforms in Bohai, are analysed through prototype measurement method. A prototype monitoring system was built in field to evaluate the ice-induce vibration risks; A prediction model was established for ice-induced acceleration forecast, based on the monitoring information; Finally the warning criterion and processes were proposed.4. The research on evaluating ice-resist design through prototype measurement methodThe researches on ice-resist design in Bohai are very hot recently. Many methodologies were proposed including the ice-break cone, the isolation technologies and so on. It is a key problem that how to test and evaluate these new methodologies used in ice-resist structures design. This dissertation proposes a method for the first time to evaluate the design through prototype measurement method. It has a very high value for the ice-resist structure design, as it can well compensate the shortcomings of the numerical analysis and the model tests in the laboratory. The main works includes the prototype monitoring on the platforms before and after the adding cone changing; the prototype monitoring on a new design ice-resist platform and the evaluation of the ice-resist design based on measured data.更多还原