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首页> 外文会议>Biennial International Pipeline Conference(IPC 2004) vol.3; 20041004-08; Calgary(CA) >LATERAL BUCKLING - TRYING TO BE LESS CONSERVATIVE
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LATERAL BUCKLING - TRYING TO BE LESS CONSERVATIVE

机译：横向屈曲-尽量少保守

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Over the last few years, lateral buckling has gone from a secondary issue to one of the major concerns in pipeline design. Not many years ago pipelines were thought of as flexible elements, which could absorb virtually any kind of displacement, but due to the trend to increase fluid temperatures and after a few major environmental accidents, it seems that lateral buckling became the major design issue. Burial was then assumed to be the only safe solution. This is the normal reaction to every traumatic experience, but now that there is alertness and that accidents are being prevented, it is once again time to re-evaluate and see where caution has become excessive and what cheaper alternatives can be used. Several papers have been written over the last 3 or 4 years addressing this issue, for instance, and, in general, one could say that there is a consensus regarding the need to know more about how pipelines move, when they buckle laterally, and to what extent they should be allowed to do so. Still another issue, which has been discussed along with this one, is related to how cyclic motions (due to cycles of heating and cooling) can aggravate the problem. Attention is drawn to the fact that the buckling analyses are usually performed based on models conceived to simplify the design, while, on the other hand, construction and installation pay a penalty, because of unnecessary conservatism, which could be avoided if a bit more effort was put into the design. Just to illustrate what is being said, let us consider a typical lateral buckling problem and how the practice has decided it should normally be treated: 1. Determine the pipeline embedment length (that for which the pipeline will build up sufficient axial friction to anchor the axial force due to the temperature variation); 2. Build a model twice that size, embedded at both ends, using a program, which can model axial and lateral friction (this is a nonlinear analysis); 3. Build a prop type lateral installation deviation at the center of the model; 4. Analyze the pipeline assuming that the expansion from both sides will build into that deviation, thus causing the pipeline to buckle at that section. In spite of having become a traditional design approach, it is associated with a conservative model. The bottom is assumed flat, the soil model is a simple elasto-plastic spring and, also, that there is only one lateral imperfection, which will concentrate all the axial expansion. The object of this paper is to show that it can be very advantageous to spend more time and money on the design, using more detailed analysis models, in order to save much more on the construction and installation. This will be done by sharing the experience gained based on the use of such models, during several recent pipeline projects, handling over 300km of pipes, with diameters varying between 6 and 34 inches in water depths ranging from 0 to 2000m.
机译：在过去的几年中，横向屈曲已从次要问题变成管道设计中的主要问题之一。几年前，管道被认为是柔性元件，几乎可以吸收任何形式的位移，但是由于流体温度不断升高的趋势以及几次重大环境事故之后，横向屈曲似乎成为主要的设计问题。然后认为埋葬是唯一安全的解决方案。这是对每一次创伤经历的正常反应，但是现在有了机警并预防了事故，是时候再次进行评估，看看谨慎在哪里变得过多，以及可以使用哪些更便宜的替代方法。例如，在过去的3或4年中针对此问题写了好几篇论文，总的来说，可以说，对于需要更多地了解管道如何移动，横向弯曲以及如何对管道进行移动达成共识。应该在多大程度上允许他们这样做。与这个问题一起讨论的又一个问题与循环运动（由于加热和冷却的循环）如何加剧该问题有关。请注意以下事实：屈曲分析通常基于旨在简化设计的模型执行，而另一方面，由于不必要的保守性，建造和安装会付出一定的代价，如果付出更多的努力可以避免被放入设计中。仅为了说明问题，让我们考虑一个典型的横向屈曲问题以及实践如何确定通常应解决的问题：1.确定管线的埋入长度（对于该埋入长度，管线将产生足够的轴向摩擦力以锚固管道由于温度变化而产生的轴向力）; 2.使用程序建立一个两倍于两端大小的模型，该程序可以对轴向和横向摩擦进行建模（这是非线性分析）； 3.在模型中心建立一个支柱式横向安装偏差； 4.分析管道，假设两侧的膨胀都将导致该偏差，从而使管道在该部分弯曲。尽管已成为传统的设计方法，但它仍与保守的模型相关联。假定底部是平坦的，土壤模型是简单的弹塑性弹簧，并且还只有一个横向缺陷，它将集中所有轴向扩展。本文的目的是表明，使用更多详细的分析模型在设计上花费更多的时间和金钱，以节省更多的建筑和安装费用，可能是非常有利的。这将通过分享在使用这些模型的过程中获得的经验来完成，该项目在最近的几个管道项目中处理了300公里以上的管道，直径在6到34英寸之间，水深在0到2000m之间。

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