【摘要】：在深海油氣工程中,海底管線系統(tǒng)十分龐大,被稱為海洋油氣資源輸送的生命線。高溫高壓下裸置海底管線的水平向整體屈曲是管線破壞的主要形式之一,是深海油氣開發(fā)面臨的重要技術挑戰(zhàn)。較大的屈曲變形一方面可能導致管線中的彎曲應力增長,接近或達到材料的屈服強度,對管線的安全運營造成威脅;另一方面可能造成管線配重層、保溫層結構破壞,影響管線的正常使用。因此開展高溫高壓下海底管線的水平向整體屈曲研究具有重要的理論意義和工程實用價值。本文基于土體對管線約束力的常系數(shù)模型,運用解析解和顯式動力數(shù)值方法分析了理想管線、含單一幾何初始缺陷管線和含非單一幾何初始缺陷管線的水平向整體屈曲特性,闡明了管線整體屈曲研究中的若干關鍵性問題。主要研究工作和創(chuàng)新性成果如下:(1)提出了基于大變形理論的整體屈曲解析分析方法,驗證了該方法的準確性,推導了理想和含單一幾何初始缺陷管線高階模態(tài)整體屈曲的解析解。工程實例分析表明,理想管線發(fā)生低階模態(tài)整體屈曲時ModelⅡ較ModelⅠ更易發(fā)生;發(fā)生高階模態(tài)整體屈曲時ModelⅣ較ModelⅢ更易發(fā)生;含單拱缺陷管線更易發(fā)生ModelⅠ的整體屈曲;含雙拱缺陷的管線更易發(fā)生ModelⅡ的整體屈曲。(2)推導了管線最優(yōu)模型長度的計算公式,揭示了幾何初始缺陷較小時屈曲變形出現(xiàn)動態(tài)跳轉(zhuǎn)現(xiàn)象的本質(zhì)。研究表明,管線最優(yōu)模型長度的大小隨初始缺陷幅值與波長比值的增加而減小,管線屈曲段內(nèi)軸力釋放量先大于后小于滑動段土阻力的增加量是動態(tài)跳轉(zhuǎn)產(chǎn)生的主要原因。(3)提出了模態(tài)分析與顯示動力相結合的數(shù)值模擬方法,實現(xiàn)了三維實體地基單元上管線整體屈曲的模擬。對比了幾何初始缺陷和干擾力激發(fā)管線發(fā)生水平向整體屈曲的區(qū)別與聯(lián)系。研究表明,運用顯示動力法模擬海底管線的整體屈曲具有可靠性,幾何初始缺陷和干擾力均可誘發(fā)管線發(fā)生整體屈曲,兩種方法沒有直接的對應關系,得到的分析結果存在偏差。(4)開展了理想管線、含單一和非單一幾何初始缺陷管線水平向整體屈曲的數(shù)值模擬,對比了數(shù)值模擬結果與解析解結果的區(qū)別,揭示了缺陷間距及組合方式對整體屈曲計算結果的影響。工程算例分析表明,管線整體屈曲的變形形態(tài)不是獨立的,是由低階向高階發(fā)展的過程;解析解與數(shù)值模擬結果的差異隨vom/L0的增加而逐漸減小;缺陷間距較小時,會出現(xiàn)屈曲疊加現(xiàn)象,不利于管線的穩(wěn)定。
[Abstract]:In deep-sea oil and gas engineering, the submarine pipeline system is very large, which is called the lifeline of offshore oil and gas resources transportation. Horizontal global buckling of bare submarine pipelines under high temperature and high pressure is one of the main forms of pipeline failure and is an important technical challenge for deep-sea oil and gas development. On the one hand, the large buckling deformation may lead to the increase of bending stress in the pipeline, approaching or reaching the yield strength of the material, which may threaten the safe operation of the pipeline; on the other hand, it may cause the damage of the weight layer and insulation layer of the pipeline, which may affect the normal use of the pipeline. Therefore, it is of great theoretical significance and practical value to carry out the study of horizontal global buckling of submarine pipelines under high temperature and high pressure. In this paper, based on the constant coefficient model of soil binding force on pipelines, the horizontal global buckling characteristics of ideal pipelines, pipelines with single geometric initial defects and pipelines with non-single geometric initial defects are analyzed by means of analytical solution and explicit dynamic numerical method, and some key problems in the study of global buckling of pipelines are expounded. The main research work and innovative results are as follows: (1) the analytical analysis method of global buckling based on large deformation theory is proposed, the accuracy of this method is verified, and the analytical solutions of high-order mode global buckling of pipelines with ideal and single geometric initial defects are derived. The analysis of engineering examples shows that Model II is more likely to occur in low-order mode global buckling than Model 鈪，

本文編號：2498785