【作者】 丁鹏；

【导师】 闫相祯；

【作者基本信息】 中国石油大学 ， 油气工程力学， 2008， 博士

【摘要】 海底管线的安全可靠性分析与风险评估是全面评价海底管线在服役过程的安全可靠性能和预期寿命,有效预防海底管线失效,提高海底管线可靠性,延长海底管线寿命的重要应用型理论研究。本文的主要研究成果有:(1)研究腐蚀海底管线的剩余强度和失效概率。总结分析了含缺陷海底管线剩余强度的计算方法和计算准则,获得多种因素对海底管线剩余强度的影响规律,并给出随服役时间变化的海底管道腐蚀缺陷剩余强度及失效压力的预测程序。通过对腐蚀缺陷海底管道剩余强度的三维非线性有限元分析,得到了缺陷方位、缺陷深度和缺陷长度的变化对缺陷最大应力的影响规律。建立腐蚀海底管线失效的极限状态方程,应用一次二阶矩法对含腐蚀缺陷海底管道的失效概率进行计算,分析海底管线强度和载荷的随机性对其可靠性的影响规律,确定海底管线失效概率的影响参数及其影响规律。(2)对海底管道缺陷评定技术及评定规范进行了深入的分析研究,为海底管道缺陷安全可靠性评定提供理论基础。根据16Mn海底管线钢的拉伸试验结果,考虑到海底管线强度、载荷、缺陷尺寸等参数具有一定的随机性,以概率断裂力学和可靠性理论为基础,采用随机数值模拟和理论计算等方法分析了海底管线强度的随机性及其影响因素。基于BS 7910评定标准,建立了含裂纹缺陷海底管线的安全可靠性评定模型,对埕岛油田某海底管线焊接接头处的表面裂纹进行了可靠性评定,给出海底管线缺陷安全评定的可靠度结果,得出了海底管线失效概率与评定参数的统计分布规律。(3)进行地质灾害作用下海底管道的安全评定分析。建立悬跨海底管道的振动方程,求解出悬跨段管道的固有频率及管道的允许悬空长度,得到水流速度、边界条件和轴向力对悬空管道的固有振动频率和极限允许跨长的影响规律。建立海底管道数值计算模型,对海底管道进行地震载荷作用下的动力响应分析,得到地震烈度、阻尼比及场地类型对海底管线抗震响应的影响规律。(4)通过理论分析及疲劳试验预测海底管线在波浪载荷作用下的疲劳寿命。设计完成了16Mn海底管线试件的拉-拉单轴成组多级疲劳试验。采用基于概率的疲劳寿命统计方法,对16Mn海底管线疲劳试验的数据进行分析处理,得出可供海底管线现场直接应用的疲劳寿命预测公式。并对海底管线焊接接头的疲劳曲线进行修正分析,得到服役海底管线焊接接头在不同存活率下的P-S-N曲线。同时,综合分析各种疲劳寿命预测公式,选择适合于海底管线实际服役过程且应用较为简单的寿命预测方法,应用海底管线的模拟疲劳试验得到的P-S-N曲线,进行海洋立管在波浪载荷作用下的疲劳寿命预测研究。(5)分析研究适合海底管线实际工况的定量风险评价模型。通过对埕岛油田海底管线系统的数据采集和资料分析,建立海底管线系统故障树分析模型,得出引起海底管线失效的主要因素。在此基础上,建立基于故障树分析的海底管线风险评估的模糊综合定量分析方法及其模型,综合分析海底管线各风险因素的影响程度和发生概率,同时考虑人为因素等难以量化或资料不完备的风险因素;对埕岛油田某段海底管线的风险情况进行实例计算和验证,计算结果表明风险评估模型具有较好的可信度。(6)开发“海底管线安全评定与风险评价系统”软件。根据上述研究成果,结合国内外相关权威规范,采用动态数据库技术、优化筛选技术和计算机图形学,完成了相关软件的开发,并将其成功应用于相关实例的计算中。更多还原

【Abstract】 Reliability analysis and risk assessment of submarine pipeline are important research of applied theory and technology used for evaluating reliability, safety and prospective life of submarine pipeline in service process including many risk factors, furthermore, preventing effectively submarine pipeline failure, increasing submarine pipeline reliability, lengthening submarine pipeline life. The major contents are summarized as follows:(1) Based on the obtained research achievement, the mechanisms of submarine pipeline failure, the influences of various typical loads on submarine pipeline failure, and the influences of multifold factors on submarine pipeline strength were attained by means of the data collection and academic deduction. The ultimate state equations of submarine pipeline were established in accordance with the basic failure forms, submarine pipeline strengths and loads. Because submarine pipeline strengths and loads are random, according to the probability and reliability theory, the computing method of failure probability of submarine pipeline was confirmed. The distributions of typical parameters were obtained through academic deduction, relational empirical formulas, and analysis of probability models of typical loads. The factors affecting submarine pipeline failure probability were determined, and the influence law of randomness of submarine pipeline strengths and loads on submarine pipeline reliability were obtained.(2) According to the tensile test result of 16Mn submarine pipeline, the parameter’s randomness such as defect size and submarine pipeline strengths were analyzed. Then, Monte Carlo numerical method was used to calculate reliability assessment for welded joints of submarine pipeline steel in Chengdao oilfield with surface flaw at the weld toe based on British standard 7910.The failure probability of submarine pipeline containing defects was worked out. The regularities and parameters of distribution of various submarine pipeline strengths, and the influences of randomness of evaluation parameters on failure probability of submarine pipeline were achieved.(3) The vibration equation of free spanning submarine pipeline was established, the natural frequency and allowable length of free spanning were solved. Influence of water flow velocity, boundary conditions and axial force on vibrating natural frequency of submarine pipeline were obtained. The numerical simulation model of seismic for submarine pipeline was established and seismic response analysis of submarine pipeline was carried on. Then influence law of damping ratio and site types on seismic response of submarine pipelines was obtained.(4) The tension-tension fatigue test of 16Mn submarine pipeline was designed. Based on the probability method of statistical analysis, the experimental data were analyzed and the formula of fatigue life estimation was obtained. The fatigue curve of welded joint for submarine pipeline was corrected, then the P-S-N curve of welded joint under different survival rate were achived. Various formulas of fatigue life were analyzed and simple but accurate for the engineering application for life prediction method was selected. Base on the simulation fatigue test of submarine pipeline, the fatigue life of riser under the wave loading were estimated by using P-S-N curve.(5) By acquiring and analyzing data of submarine pipeline system for Chengdao Oilfield, the model of fault tree analysis is set up and main factors caused by submarine pipeline failure were founded. The fuzzy compositive quantitative risk assessment method and model of submarine pipeline based on fault tree analysis were established. The influence grade and occurrence probability of risk factors of submarine pipeline were analyzed synthetically, and these risk factors include human error and others which are difficult to be quantified or short of data. The risk assessment of a practical submarine pipeline was completed in order to verify the risk assessment model. The result shows that the risk assessment model is reasonable and practical.(6) According to the aforementioned achievement, the software“Reliability and Safety Analysis of Submarine pipeline”was developed and applied to evaluate the security of submarine pipeline successfully based on dynamic database, optimizing filtration technology and computer graphics.更多还原