【作者】 陈博文；

【导师】 梁德志；

【作者基本信息】 沈阳建筑大学 ， 防灾减灾工程及防护工程， 2011， 硕士

【摘要】 随着海洋油气资源的开发和利用,作为油气集输环节中重要设施的海底管道的应用也日益增多。海底管道在铺设和服役期间会不可避免的形成悬跨段,而悬跨段在涡激振动下的频率锁定现象是导致管道断裂失效的主要因素。为探索海底悬跨管道在复杂荷载作用下的损伤、破坏机理,为其损伤监测评估方法和技术的发展以及灾害防治对策的制定提供理论基础和科学依据,本文通过理论公式推导,物理模型试验和有限元模拟,对海底悬跨管道的动力特性和动力响应展开相关研究。海底悬跨管道在自身重量、内部流体、外部荷载作用下会出现静力破坏及动力破坏的可能,且海底管道悬跨管段的长度又是决定管道静力破坏与动力破坏的关键因素,本文把避免出现涡激振动作为控制条件,推导了不同边界条件下的管道自振频率公式,计算了管道在垂直流向振动下的最大允许悬跨长度。计算结果表明,海底管道的允许跨长与管道悬跨两端边界条件有关,固端支撑下的管道最大允许悬跨长度是简支情况下的1.5倍。针对悬空段,介绍了相应的治理措施,具体介绍了水下支撑固定法的施工方法和施工步骤。针对海底悬跨管道动力特性影响因素的复杂性,本文利用MTS水下振动台模拟了海底悬跨管道在地震波输入下的动力反应。试验考虑了地震波输入方向、管内运输物质、悬跨高度、水深以及不同种地震波输入等因素,完成了不同工况组合下的多组实验。试验结果显示在相同幅值输入下,海底悬跨管道在水平地震输入时的动力反应要大于在竖向地震输入时的动力反应;在正弦波输入下,管道跨中反应随着管内含沙量的增加而减小,在深水域和悬高较大时管道跨中加速度变化比较平稳,在水平El Centro波输入下管道跨中应变呈增大趋势。本文利用ABAQUS有限元分析软件对水上空管试验模型进行了正弦波和El Centro模拟地震波输入下的动力分析,并与试验结果进行比较。比较结果显示,ABAQUS在计算模型固有频率时误差很小;应力云图符合模型实际变化情况;地震波输入下各测点的加速度放大系数沿管轴分布结果符合较好;El Centro波输入下管道跨中加速度反应功率谱密度曲线中加速度峰值对应的共响频率基本一致。说明ABAQUS能较好的模拟地震波输入下管道的动力响应问题。更多还原

【Abstract】 Submarine pipelines, as the important establishment of oil-gas transmission, have been more widely used with offshore oil-gas exploitation and application. Free span will inevitably form in commission, the frequency lock-in under VIV is the key factor to lead to the destruction of pipelines.To provide theoretical foundation and scientific basis for disaster process, damage mechanism and safe assessment of submarine pipelines in an offshore environmental condition, investigations have been conducted on dynamic response of submarine suspended pipeline, based on formula deduction, model tests and numerical simulation.Free spanning submarine pipelines are complicated systems with soil-pipe-fluid interaction under dead load, internal fluid, external environment and dynamic load, and the span length is the major factor to decide the static and dynamic destruction. Taking to avoid vortex induced vibration (VIV) as the control condition, this paper gives the formula of allowable span length under in-line motion, deduces the formula of natural frequency of pipeline on different boundary conditions, and calculates the allowable span length under cross-flow motion. The results show that boundary conditions have large affect on allowable span length, which of fixed support is larger than that of simply support; the paper introduces construction principals and the measures of fixing support under water for the free spanning pipeline.Due to the complication of effect factors of free spanning submarine pipelines, the dynamic response in earthquake is studied by using an underwater shaking table. Experiments on many groups of different combinations of factors including seismic wave direction, transmitting materials, distance from seabed, water depth and the kind of wave are carried out. The results show that the dynamic response under horizontal seismic input is larger than that under vertical seismic input at the same amplitude; under sine wave, the dynamic response of pipeline of mid span declines as the sediment concentration increases, but becomes stable when the pipeline is in deep water and longer distance from seabed; under horizontal El Centro wave, the strain of mid span raised as water depth and distance from seabed increases.Numerical analysis of free terrestrial spanning pipeline is carried out using finite element software ABAQUS. The relative results show that calculation error of the natural frequency is little; stress nephogram is in good agreement with experimental condition, the variance of magnification of acceleration along the axial direction conforms to experimental condition, under seismic wave, the numerical value of resonance frequency accords with experimental value. So ABAQUS can simulate the dynamic response of pipeline under seismic wave accurately.更多还原