径向压力作用下非粘结柔性管极限承载力研究

发布时间：2018-02-01 19:23

本文关键词： 非粘结柔性管极限承载力受限压溃爆破内压　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：随着能源需求不断增加,油气资源的开采逐渐从陆地和浅海向深海进军,海洋立管与海底管道作为其中重要的工程装备面临着更多挑战。由于自身结构和材料特点,非粘结柔性管(注:后文均简称为非粘管)有着较强的抗拉、抗内外压承载力以及较小的抗弯刚度,相比于传统钢管有更优良的弯曲顺应性和耐腐蚀性,成为深海油气管线很好的选择。而在环境条件复杂多变的深水或超深水中,控制超过非粘管自身极限承载能力的失效模式是非常重要的,一旦失效发生可能引发一系列工程事故,造成不可估量的经济损失和环境污染,因此需要对非粘管极限承载能力进行深入研究,以便后续有效地指导非粘管设计。本文主要研究的是内外压力载荷下非粘管的截面力学性能,包括非粘管在外压下的压溃破坏及内压下的爆破失效。对于压溃破坏,重点研究外护套破损后外部压力作用在非粘管内护套外壁时的湿压溃模式,本文将该问题简化为非粘管内层的受限屈曲问题;对内压爆破,采用了原型截面的三维模型进行数值模拟,研究影响非粘管爆破压力的因素。具体来说,本文的研究内容主要包括:(1)受弹性限制的圆管外压屈曲理论研究。分析总结了圆管在外压下的屈曲理论,使用弹簧约束模拟外层限制,利用势能原理推导了受弹性限制的圆管屈曲理论公式。(2)双层弹性非粘管受限内层压溃数值研究。采用通用有限元程序ABAQUS,建立二维平面模型,使用弧长法研究内外层弯曲刚度比、内层径厚比对内层受限压溃的影响,总结了受限内层的失稳模态,并基于数值分析结果,拟合出计算公式,与解析解进行对比;建立三维内层螺旋缠绕结构模型,计入缺陷影响,使用动态隐式算法研究内外层弯曲刚度比、内层径厚比对螺旋内层受限压溃的影响,总结了受限螺旋内层的失稳模态,提出设计公式。(3)弹性非粘管受限内层压溃参数分析。采用二维平面模型动态隐式算法,分别研究层间摩擦力、内层不圆度、层间间隙、内层不均匀厚度对内层压溃承载力的影响;在双层平面模型中加入中间层模拟骨架层与铠装层之间的内护套,研究内护套对受限压溃的影响。(4)双层非粘管受限弹塑性内层压溃数值研究。内层材料分别采用理想弹塑性和双线性硬化模型,研究了内层材料屈服强度以及硬化率对受限内管的压溃承载力影响,结合弹性非粘管受限压溃公式拟合弹塑性受限压溃公式。(5)非粘管压溃实验研究。采用两种钢带缠绕非粘管进行外护套完整的整体外压压溃试验和外护套破损的受限内管压溃试验。并将结果与有限元分析、计算公式进行对比,验证计算公式的正确性。(6)内压下非粘管爆破压力研究。采用考虑材料非线性的理论方法与精细化ABAQUS有限元模型结果进行对比,同时分析拉伸对爆破压力的影响。
[Abstract]:With the increasing demand for energy, the exploitation of oil and gas resources gradually advances from land and shallow sea to the deep sea. As one of the important engineering equipment, marine riser and submarine pipeline are facing more challenges. Due to their own structure and material characteristics, non-bonded flexible pipe (note: referred to as non-adhesive pipe) has a strong tensile resistance. Compared with the traditional steel pipe, the internal and external compressive capacity and the small bending stiffness have better bending compliance and corrosion resistance. It is very important to control the failure mode beyond the limit load capacity of non-viscous pipe in deep water or ultra-deep water with complex and changeable environmental conditions. Once failure occurs, it may lead to a series of engineering accidents, resulting in incalculable economic losses and environmental pollution. Therefore, it is necessary to study the ultimate bearing capacity of non-adhesive pipes. In order to guide the design of non-stick pipe effectively, this paper mainly studies the cross-section mechanical properties of non-stick pipe under internal and external pressure. Including the failure of non-stick pipe under external pressure and the failure of blasting under internal pressure. For crushing failure, emphasis is placed on the wet crushing mode of the external pressure acting on the outer wall of the non-viscous pipe after the damage of the outer sheath. In this paper, the problem is simplified as a constrained buckling problem of the inner layer of a non-viscous pipe. For the internal pressure blasting, the three-dimensional model of the prototype section is used to simulate the factors that affect the blasting pressure of the non-stick pipe. Specifically, the factors affecting the pressure of the non-viscous tube blasting are studied. The research contents of this paper mainly include: (1) the elastic buckling theory of circular pipe under external pressure is analyzed and summarized, and the spring constraint is used to simulate the outer limit. By using the potential energy principle, the elastic buckling theory formula of circular pipe is derived. The numerical study of double layer elastic non-viscous pipe is studied. The general finite element program Abaqus is used to establish a two-dimensional plane model. The influence of the ratio of internal and external bending stiffness and the ratio of inner diameter to thickness is studied by arc length method. The instability modes of the inner layer are summarized, and the calculation formula is fitted based on the results of numerical analysis. Compared with analytical solution; In this paper, a three-dimensional spiral winding structure model is established, which takes into account the effect of defects. The dynamic implicit algorithm is used to study the effect of the ratio of bending stiffness and the ratio of diameter to thickness of the inner layer on the confined collapse of the inner spiral layer. The unstable modes of the confined spiral inner layer are summarized, and the design formula. 3) the buckling parameter analysis of the confined inner layer of the elastic non-viscous pipe is presented. The dynamic implicit algorithm of two-dimensional plane model is used to study the friction between the layers respectively. The influence of inner layer non-roundness, interlaminar gap and inner layer non-uniform thickness on inner laminar crushing capacity; The inner sheath between the skeleton layer and the sheathed layer is added to the double-layer plane model. The effect of inner sheathing on confined buckling is studied. (4) numerical study of double layer non-viscous pipe confined elastic-plastic inner lamination. Ideal elastic-plastic model and bilinear hardening model are used for inner layer material respectively. The effect of yield strength and hardening rate of inner layer material on the crushing capacity of confined inner pipe was studied. Fitting Elastic-plastic confined burst Formula with Elastic Non-viscous Pipe confined burst Formula. 5). Two kinds of steel strip wound non-stick pipe were used to complete the whole external crushing test and the limited inner pipe crushing test of the outer sheath failure. The results were analyzed with finite element method. The formulas are compared. Verify the correctness of the formula. 6) the pressure of non-viscous pipe blasting under internal pressure. The theoretical method considering material nonlinearity is compared with the results of refined ABAQUS finite element model. At the same time, the influence of tension on blasting pressure is analyzed.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TE973.92

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