【作者】 李涛；

【导师】 卢青针；

【作者基本信息】 大连理工大学 ， 工程力学， 2019， 硕士

【摘要】 在海洋资源开发过程中,各种结构形式的钢管和柔性管道是输送油气资源的主要装备,面对复杂苛刻的海洋环境,管道抵抗各种荷载的性能至关重要,其中管道的抗外压性能越来越成为各类油气输送管道的重要评价指标。抗外压性能受到多种因素的影响,既有自身材料和结构的影响,也有其它复杂组合荷载的影响,这给海洋油气输送管道的设计带来很大的不便。本文以无缝钢管和钢带加强型柔性管道为研究对象对多因素影响下的海洋管道抗压溃性能进行了分析。研究采用理论、实验、有限元相结合的方式展开,以理论为基础剖析压溃机理,以实验结果为指导验证理论分析和有限元模型的正确性,以有限元分析为主要研究手段,通过大量的仿真计算研究各因素对管道抗压溃性能的影响规律。文中首先对各种压溃理论进行了总结,包括经典弹性压溃理论、塑性压溃理论、DNV规范等,并对其适用性进行了讨论。随后设计实验研究了初始椭圆度、弯曲荷载的影响,并基于实验结果进行有限元分析,研究表明:初始椭圆度、弯曲荷载是影响抗压溃性能的重要因素,初始椭圆度或弯曲荷载的增加都会使极限压溃值显著下降。材料屈服强度、管道所受拉伸荷载对抗压溃性能有一定的影响,但影响很小,在抗压溃设计中可以选择强度较低的钢材,在满足抗外压性能需求的同时可以节约经济成本。在椭圆度和弯曲荷载联合作用的工况中,弯曲荷载和初始椭圆度方向之间的夹角θ是影响管道抗压溃性能的一个主要因素。极限压溃值随着θ的增大逐渐变大,θ为0°时极限压溃值最小,θ为90°时极限压溃值最大,且极限压溃值p和角度θ的关系符合指数型函数p=e^A+Bθ+Cθ2对夹角θ的合理控制可以使管道的抗压溃性能得到提升,且初始椭圆度越大的管道抗压溃性能提升的空间越大。采用实验和有限元的方法对钢带加强型柔性管道的抗压溃性能进行研究,研究结果表明:钢带加强型柔性管各层结构之间摩擦系数的增大可以增加极限压溃值。钢带屈服强度小于100MPa时会使柔性管抗压溃性能降低,钢带的屈服强度在大于200MPa后继续增加对钢带加强型柔性管道的抗压溃能力影响不大,基于经济性原则考虑可以选择强度较低的钢带结构。更多还原

【Abstract】 In the process of marine resources development,various structural forms of steel pipes and flexible pipes are the main equipment to transport oil and gas resources.In the face of complex and harsh marine environment,the performance of pipes against various loads is very important,and the performance of pipelines against external pressure has increasingly become an important evaluation index for various types of oil and gas pipelines.External pressure resistance is affected by many factors,including material and structure,and other complex combined loads,which brings great inconvenience to the design of offshore oil and gas pipelines.In this paper,seamless steel pipe and steel strip reinforced flexible pipe are taken as research objects to analyze the collapse resistance of marine pipes under the influence of multiple factors.The research is carried out by combining theory,experiment and finite element method.The collapse mechanism is analyzed on the basis of theory.The correctness of theoretical analysis and finite element model is verified by experimental results.The main research method is finite element analysis.The influences of various factors on collapse resistance of pipes is studied through a large number of simulation calculations.Firstly,various collapse theories are summarized,including classical elastic collapse theory,plastic collapse theory and DNV code,and their applicability is discussed.Subsequently,the influence of initial ellipticity and bending load is studied by design experiments.Based on the experimental results,the finite element analysis is carried out.The results show that the initial ellipticity and bending load are the important factors affecting the collapse performance.The increase of initial ellipticity or bending load will significantly reduce the ultimate collapse pressure.The yield strength of materials and the tensile load on pipes have some influence on the collapse performance,but the influence is very small.In the collapse design,the steel with lower strength can be selected to meet the requirement of external compressive performance and save economic cost.In the case of combined action of ellipticity and bending load,the angleθbetween bending load and initial ellipticity direction is a major factor affecting the collapse resistance of pipes.The ultimate collapse pressure gradually increases with the increase ofθ.The minimum is at 0°and the maximum is at 90°,and the ultimate collapse pressure p and angleθcoincide with exponential function p=e^A+Bθ+Cθ2.In the installation of pipes,the collapse resistance of pipes can be improved by reasonable control of angleθ,and the greater the initial ellipticity,the greater the space for improving the collapse resistance of pipes.The experimental and finite element methods are used to study the collapse resistance of steel strip reinforced flexible pipes.The results show that the collapse pressure can be increased with the increase of friction coefficient between layers.When the yield limit of steel strip is less than 100 MPa,the collapse resistance of flexible pipe reduces.The increase of yield limit of steel strip after 200 MPa has little effect on the collapse resistance of steel strip reinforced flexible pipes.So the steel strip structure with lower strength can be selected based on the principle of economy.更多还原