深水夹层复合管侧向屈曲机理与控制技术研究

The deepwater oil and gas pipelines should have excellent thermal insulation properties because of low temperature and high pressure. Sandwich pipes, with high load-carrying capacity and excellent thermal insulation property, can be the effective solution for the deepwater submarine pipelines. However, due to high temperature and internal pressure, the deepwater sandwich pipes tend to buckle laterally that may lead to fatigue or fracture. It is a huge challenging to accurately analyze the lateral buckling response of sandwich pipes and to control it effectively because of the complex structure and interaction between middle layer and inner or outer pipes. The studies and recommended practices focusing on lateral buckling of sandwich pipes are lacking. Experimental tests, theoretical model analysis and numerical calculation are used in this project to study the lateral buckling of sandwich pipes. At the same time, the control technology for lateral buckling of sandwich pipes is also studied based on the sleeper method. There are two aims of this project. One is to reveal the relationship between critical buckling force and structure parameters, material parameters, imperfections, vertical loads, lateral resistance, as well as interaction between middle layer and inner or outer pipes. The other aim is to build the control standard for lateral buckling of sandwich pipes. These all contribute to build the control theory and technology of lateral buckling for the application of sandwich pipes in deepwater or ultra-deepwater.

深水高压低温的环境特点决定了深水油气管道需要具有较好的保温绝热性能。深水夹层复合管，由于具有较高的结构强度和良好的保温绝热性能，近年来被认为是有效的深水油气管道解决方案。但在其内部高温和高压环境下，深水夹层复合管容易发生侧向屈曲而导致管道疲劳或断裂等失效形式。深水夹层管是一种复合结构，层间相互作用复杂，准确描述其侧向屈曲特性并开展侧向屈曲控制具有很大挑战，到目前为止国内外研究和规范也鲜有涉及。本项目拟采用实验研究、理论分析和数值模拟相结合的方法，研究夹层管侧向屈曲机理，揭示夹层管侧向屈曲临界轴力与夹层管的结构参数、材料参数、初始缺陷、竖向载荷、侧向约束力以及层间相互作用等之间的内在联系。同时，结合枕木法研究夹层管侧向屈曲响应参数与枕木结构参数之间的关系，建立夹层管侧向屈曲控制准则，为夹层管在深水和超深水油气资源开发工程中的应用奠定重要的理论和技术基础。

深水管壳结构在外部静水压力载荷或内部高温高压载荷下容易发生屈曲而导致最终结构破坏，从而造成重大的经济损失。深水复合管壳结构的屈曲机理以及屈曲有效控制问题是深水工程装备的设计难题。本项目首先开展了深水复合管壳结构的层间剪切和轴向推出试验，得到复合管壳结构环向和轴向相互作用模型，在此基础上建立了深水管壳结构数值分析模型，系统研究了材料参数、结构参数、初始缺陷、管土相互作用对深水管壳结构屈曲临界力的影响规律，得到了考虑以上影响因素的深水管壳结构屈曲临界力预测公式；同时研究了厚壁深水管壳结构的屈曲与强度失效交互机制，分析了长径比、厚径比、铺层角度和顺序对深水复合管壳结构的屈曲临界力和强度失效压力的影响规律，提出了预测厚壁深水复合管壳结构屈曲临界力和强度失效压力的预测模型；最后针对深水管壳结构的抗屈曲设计提出了预置缺陷法，通过控制其外表面和内表面轮廓曲线大大提高深水管壳结构的抗屈曲能力，提出了这种方法下深水管壳结构屈曲临界力的理论解，对于深水工程装备中管壳结构的抗屈曲设计提供了理论支撑与技术支持。